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

Fact 2: Darwinism is strictly, selection theory.

Given the two facts above, answer the question "what describes behaviors that improve fitness?" with the following options: 
- staying warm
 - mass
 - Darwinism
 - Riding a bike
 - death
 - survive
 - density
 - positive


 

   Darwinism      