Maria and sarah made a set of paper cup telephones. first the girls punched a hole in the bottom of each cup. then they connected the cups with a very long piece of string, knotted in the bottom of each cup. maria went down the hall to her bedroom while sarah stayed in the kitchen. when maria put the cup to her ear she could hear sarah talking to her because.

a) they were not that far from each other.
b) sound waves traveled through the string to maria’s cup.
c) sound waves traveled through the air from room to room.
d) sound waves bounced off of the walls to reach maria in the bedroom.