Fact 1: The gravitational pull of the Moon on Earth 's oceans causes the tides.

Fact 2: Earth Day celebrations are now held across the world.

Given the two facts above, answer the question "What does gravitational pull of the moon cause?" with the following options: 
- tides
 - waves
 - heat
 - gravitational pull of the sun
 - rain
 - the world's orbit
 - motion
 - erosion


 

 tides        