Question

which is true about visible light? it cannot travel through a vacuum. it travels fastest through a medium, such as water or air. it is the only part of the electromagnetic spectrum that we can see.

Explanation:

Visible light is a part of the electromagnetic spectrum. Electromagnetic waves, including visible light, can travel through a vacuum (so the first option is false). Light travels fastest in a vacuum, not in a medium like water or air (so the second option is false). By definition, visible light is the portion of the electromagnetic spectrum that the human eye can detect.

Answer:

It is the only part of the electromagnetic spectrum that we can see.