Katia was listening to music on the radio. In order for the sound to be produced, the electrical energy must be converted into which type of energy?
A: mechanical energy

While studying the relationship between number of trees and amount of atmospheric oxygen, which of the following would be most important to take into account?
A: contributions to atmospheric oxygen from sources other than trees

What is the best way for a marine scientist to determine the eating habits of sharks?
A: Tag several sharks and monitor their eating habits for one year.

After a rainstorm, a big pile of rocks blocks part of a mountain road. Which event most likely caused the rocks to move onto the road?
A:
a landslide