Fact 1: Aplanet rotating causes cycles of day and night on that planet.

Fact 2: The gravitational pull of the major planets alters the orbital period from revolution to revolution.

Given the two facts above, answer the question "What causes day and night?" with the following options: 
- chemical messengers
 - The moon
 - The ocean's waves
 - chemical reaction
 - Revolution around the sun
 - The clock on the wall
 - Evaporation of water
 - Basic units of the plant body.


 

     Revolution around the sun    