Fact 1: The moon revolving around the Earth causes the phases of the moon.

Fact 2: Tides are cyclical and closely follow the phases of the moon.

Given the two facts above, answer the question "What occurs in water as the moon revolves around Earth?" with the following options: 
- tides
 - gravity
 - liquid
 - energy
 - pollution
 - heat
 - earthquakes
 - erosion


 

 tides        