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

Fact 2: Natural selection is differential reproduction.

Given the two facts above, answer the question "Behaviors that improve fitness increase through" with the following options: 
- differential reproduction
 - produce offspring
 - biological diversity
 - metabolic reaction
 - recovery time from fatigue
 - characteristics
 - barks and snarls
 - members of their own species


 

 differential reproduction        