Which of the following statements describes a compound machine?

A. It has movement in only one direction.

B. It can only be acted on by one force.

C. It is made up of more than one simple machine.

D. It makes work more difficult.

From the word compound, the compound machine is already a combination of two or more types of simple machine. Thus, the answer is letter C. Because of its complexity, it is able to perform several other functions than a simple one.