Fact 1: Unequal heating of Earth 's surface by the Sun causes global wind patterns.

Fact 2: Another major type of wind is called a polar easterly.

Given the two facts above, answer the question "Unequal heating of Earth 's surface by what causes polar easterlies?" with the following options: 
- sun
 - UV
 - drag
 - wind
 - loch
 - ovens
 - lightbulbs
 - blankets


 

 sun        