The correct answer is option 4 - Red. The question asks for the color with the highest wavelength. In the visible light spectrum, different colors have different wavelengths. Violet has the shortest wavelength, followed by blue, green, yellow, orange, and then red, which has the longest wavelength.

Wavelength is the distance between consecutive wave peaks or troughs. In other words, it represents the distance covered by one complete cycle of a wave. The higher the wavelength, the longer the distance covered by each cycle.

Violet light has the shortest wavelength among visible colors, which means it has a higher frequency and energy. As we move towards the opposite end of the spectrum, the wavelength of light increases. Red light has the longest wavelength, which indicates lower frequency and energy.

Therefore, out of the given options, red has the highest wavelength. It is important to note that colors beyond the visible spectrum, such as infrared and radio waves, have even longer wavelengths.