Answer:
<u><em>C.)</em></u>  <em>Crest to trough</em>
 
        
             
        
        
        
Answer:
It is important to understand the difference between rotations and revolutions. When an object turns around an internal axis (like the Earth turns around its axis) it is called a rotation. When an object circles an external axis (like the Earth circles the sun) it is called a revolution.