Gary and mary stand 15 meters apart and speak to one another. they are able to hear each other because sound waves travel the distance between them through the air. next, gary and mary speak to each other through can-and-string telephones, still standing 15 meters apart and pulling the string taut. if the sound waves travel through the string, they will
a. travel at a greater speed than through the air.
b. travel at a slower speed than through the air.
c. travel at a greater amplitude than through the air.
d. travel at a lower amplitude than through the air.