The correct answer is option 1, Cathode-rays.

Cathode-rays are not electromagnetic in nature. While X-rays, gamma-rays, and infrared-rays are all forms of electromagnetic radiation, cathode-rays are streams of electrons that are produced when a high voltage is applied across electrodes within a cathode-ray tube. Unlike electromagnetic radiation, cathode-rays are charged particles, specifically electrons, and they behave differently compared to electromagnetic waves.

X-rays, gamma-rays, and infrared-rays all consist of photons, which are particles of light. X-rays have a higher energy than visible light and can penetrate through materials, making them useful for medical imaging and security screening. Gamma-rays are even higher in energy and are commonly emitted during radioactive decay or nuclear reactions. Infrared-rays have a lower energy than visible light and are often associated with heat, making them useful for thermal imaging and remote controls.

Cathode-rays, on the other hand, are a stream of electrons that can be deflected by electric or magnetic fields. They were studied extensively in the late 19th and early 20th centuries and played a crucial role in the development of television and other electronic devices.