Fact 1: Behaviors that improve fitness increase through natural selection.

Fact 2: Natural selection is the mechanism of evolution.

Given the two facts above, answer the question "How do behaviors that improve fitness increase?" with the following options: 
- because of Darwin
 - competition
 - due to fertilization
 - due to asexual reproduction
 - through evolution
 - the body's largest organ
 - Earth orbiting the Sun
 - Riding a bike


 

     through evolution    