an electromagnetic wave.... a. never moves b. can travel only through empty spaces?

D

You can see the light from the sun, can you not? that means it can travel through empty space.

And, you can see it through a pane of glass, which means it can travel through matter.

However, with EM waves and matter, there is a lot of variation. Light cannot travel through a piece of steel, nor can radio waves. but both can travel through air. Some radio waves can travel through glass, some cannot. Light can travel through water, radio cannot. Radio waves (some of them) can travel through wood, but light cannot.