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

Fact 2: Many organism behaviors have evolved through natural selection.

Given the two facts above, answer the question "What is one of the facets of an organism's evolution?" with the following options: 
- resistance
 - fitness
 - properties
 - thirst
 - movement
 - swimming
 - offspring
 - recycling


 

  fitness       