With reference to Visible Light Communication (VLC) technology, which of the following statements are correct ? 1. VLC uses electromagnetic spectrum wavelengths 375 to 780 nm. 2. VLC is known as long-range optical wireless communication. 3. VLC can transmit large amounts of data faster than Bluetooth. 4. VLC has no electromagnetic interference. Select the correct answer using the code given below :

Explicitly names visible light as 'short waves' of the Sun's radiation and contrasts visible with ultraviolet and infrared bands, placing visible light within the electromagnetic spectrum.

A student could use a standard EM-spectrum chart to read off the wavelength band labelled 'visible' and thus infer the range VLC would use.

Gives a comparative rule that red light has a longer wavelength than blue (≈1.8×), identifying visible light as a band containing distinct colours with different wavelengths.

Combine this pattern with a colour-to-wavelength table (blue to red span) to estimate the numerical wavelength limits for visible light relevant to VLC.

States a general scattering rule linking wavelength to interaction with particles (wavelength vs particle radius), implying wavelength is a defining physical property of 'light' relevant for communication channels.

Use the scattering rule plus known particle sizes (or charts) to confirm that the band used in VLC behaves like visible light in atmospheric scattering, consistent with the visible band on the EM spectrum.

Refers to '7 colours in the visible part of spectrum' and distinguishes visible from ultraviolet, reinforcing that visible light is a defined segment of the EM spectrum.

A student could map those seven colours to standard wavelength intervals to determine the span VLC would occupy.

Notes 'Most sources of visible light' and discusses scattering/reflection of visible light, linking practical light sources to the visible portion of the spectrum used in lighting and thus in optical communication.

Relate common light sources used in VLC (LEDs, lamps) to the visible spectral band from lighting specifications to infer the communication wavelength range.

Notes that most visible-light sources (except lasers) emit in many directions and that light can scatter into the atmosphere, implying non-directional emission and atmospheric scattering affect propagation.

A student could combine this with knowledge of free-space link loss and directional beam requirements to judge whether typical VLC sources can sustain long-range links.

Explains scattering phenomena (e.g., blue sky) showing that visible light is scattered by particles, which alters beam propagation over distance.

Use standard atmospheric scattering facts (Rayleigh/Mie) to estimate attenuation of visible wavelengths and assess feasible VLC range outdoors.

States that light generally travels in straight lines (rays) and exhibits diffraction around small obstacles, indicating VLC would typically require line-of-sight or narrow beams.

Combine with line-of-sight constraints and terrain/obstacle layouts (e.g., maps) to judge whether long-range VLC links are practical.

Describes optic fiber cables as the means for transmitting large quantities of data rapidly and securely, highlighting that long-distance optical communication is commonly implemented via guided (fiber) rather than unguided visible-light links.

Contrast fiber-based long-range optical comm (low loss, guided) with free-space VLC to infer that 'optical' long-range comm is often fiber-based, so VLC may not be the typical long-range solution.

Reiterates the prominence of optic fiber cables for high-capacity communication, reinforcing that long-haul optical systems are primarily fiber-based.

A student could weigh the prevalence of fiber for long-haul against VLC use-cases (local/indoor) to assess classification as long-range.

States that optical fibre (light-based) systems allow large quantities of data to be transmitted rapidly, showing that light can carry high data rates.

A student can note that if guided visible/optical systems support high rates, free‑space visible light (VLC) might also offer larger bandwidth than typical radio links like Bluetooth.

Mentions use of lasers (coherent visible light) and their straight-line propagation, indicating visible light can be tightly directed and used as a controlled communication beam.

Combine with the idea that directional, coherent carriers can support higher spectral efficiency and less interference than omnidirectional radio, suggesting potential for higher VLC rates.

Notes most visible light sources (except lasers) emit in many directions and scatter, implying propagation differences between visible light and radio signals.

A student could contrast directional requirements and scattering loss of VLC with Bluetooth's omnidirectional radio behaviour to assess practical throughput and link reliability trade-offs.

Explains that electromagnetic wave behaviour (propagation/absorption) depends on frequency, implying different bands have different propagation and usage constraints.

Using basic fact that visible light frequencies are far higher than Bluetooth's radio band, a student can infer visible light offers larger available bandwidth and thus potential for higher data rates.

Describes transmission and reflection of light through media, showing light can be transmitted/controlled through materials or line‑of‑sight channels.

A student might combine this with knowledge of line‑of‑sight VLC links (and low interference) to judge that VLC could achieve high localized data rates compared with Bluetooth.

States that visible light is part of the electromagnetic spectrum (short-wave radiation), establishing VLC uses EM radiation in the visible band.

A student could combine this with the fact that EMI usually refers to interference in radio/near-RF bands to reason that interference behavior may differ across bands.

Explains that radio waves interact with the ionosphere and that different frequency bands experience different propagation and interference effects.

One can extend this pattern to infer that since visible light and radio waves occupy different frequencies, they may be subject to different sources and types of interference.

Emphasizes that wavelength/frequency determines how EM waves interact with the environment (reflection/propagation), giving a rule that interference depends on frequency range.

A student could apply this rule to VLC by noting visible-light frequencies are much higher and typically use line-of-sight propagation, so common RF-type EMI mechanisms may not apply.

Notes that optical fibre communications transmit data rapidly and are 'virtually error-free', illustrating that optical (light-based) communications can be less affected by certain electrical interferences.

Using basic knowledge that fibre optics are immune to RF EMI, a student could cautiously reason that free-space visible-light links might similarly avoid many RF interference sources, though environment differs.

Describes light scattering and interactions with particles, showing visible light is affected by atmospheric scattering and obstacles.

A student could extend this to suspect VLC is vulnerable to optical disturbances (scattering, blockages) even if it avoids typical RF EMI, so 'free from EMI' may be qualified rather than absolute.