You are presented with the question "What does does the gravitational pull of the Moon on Earth's oceans cause?" and the following answer choices: 
- deer calls
 - waves
 - rivers
 - two
 - erosion
 - trees
 - Energy.
 - moon cycles

Now knowing that the gravitational pull of the Moon on Earth 's oceans causes the tides and high tide is the crest of the wave and low tide the trough, choose the best answer.


 

  waves       