Fact 1: An egg requires warmth to survive.

Fact 2: Inside the egg, the developing rattlesnake is nourished by the yolk of the egg.

Given the two facts above, answer the question "a developing rattlesnake requires what to survive" with the following options: 
- warmth
 - companionship
 - nutrients
 - shade
 - desert
 - food
 - energy
 - air


 

 warmth        