Electromagnetic waves are transverse waves. Electromagnetic waves have very low velocity. Electromagnetic waves are all visible to human eyes. Electromagnetic waves can travel through a vacuum.
I gave my students this multiple choice question: What property of electromagnetic waves makes it possible to use these waves to transmit information between a space shuttle and NASA mission control centers on the ground?

Only one answer is correct among these 4 choices:
- Electromagnetic waves are transverse waves.
- Electromagnetic waves have very low velocity.
- Electromagnetic waves are all visible to human eyes.
- Electromagnetic waves can travel through a vacuum.

Could you tell me which one is correct?

Electromagnetic waves can travel through a vacuum.