Answer: B.Electromagnetic waves don't require a medium to travel.
Explanation:
Electromagnetic waves can travel both in space as well as medium. These are transverse waves i.e. when they travel in medium, the medium particles vibrate perpendicular to the direction of motion of wave.
A electromagnetic wave is composed of electric and magnetic fields perpendicular to each other. These fields generate each other and that is the way an electromagnetic wave carries energy forward. An electromagnetic wave travels at the speed of light in space and slows down in medium. So, the correct answer is that an electromagnetic wave does not require a medium to travel. It can travel in space.