Science question - matter?

Question

When light enters matter,
a. it can slow down or speed up.
b. stops.
c. travels at 300 000 km/s.
d. travels at the speed of sound.

Is it A?

Answer 1

You are correct. It's A.
It certainly doesn't stop (you wouldn't see the relected light from objects any more) and C and D are just silly.