Answer: The correct answer is "visible rays".
Step-by-step explanation:
Electromagnetic wave: In electromagnetic wave, both the electric fields and the magnetic field are directed in the direction of the propagation of the electromagnetic wave. Electromagnetic wave travels in vacuum.
It travels with the speed of the light.
For example, X-rays, gamma rays, infrared rays and visible region.
The electromagnetic spectrum consists of visible region and an invisible region.
Visible region of the electromagnetic can be seen by naked eyes. Its range is 400 nm to 700 nm.
We are unable to see infrared rays, ultraviolet light and gamma rays.
Therefore, the correct option is (b).