Fact 1: An egg requires warmth to survive.

Fact 2: First the frog lays the eggs, then the warmth from the sun makes the eggs hatch into baby tadpoles.

Given the two facts above, answer the question "what keeps eggs warm?" with the following options: 
- ice
 - hair
 - wool
 - bears
 - fur
 - sun
 - moss
 - sand


 

      sun   