Fact 1: When the seasons change from the summer to the fall , the amount of daylight will decrease.

Fact 2: All daylight contains a large UV component.

Given the two facts above, answer the question "What will decrease when seasons change from summer to fall?" with the following options: 
- pH
 - history
 - darkness
 - RNA
 - UV
 - Sun
 - N
 - fun


 

     UV    