Johnny is tapping his foot softly on the ground. When Melanie is standing up, she can barely hear his foot tapping. But if she puts her ear on the floor, the sound is very loud.

Why is this?
A.
Sound waves travel faster through air than through solids.
B.
Sound waves reflect off of light particles.
C.
Sound waves can travel farther through solids.
D.
Sound waves are blocked by other sound waves.