Fact 1: Evaporation of sweat uses energy, and the energy comes from body heat.

Fact 2: Energy is the body's fuel.

Given the two facts above, answer the question "What powers sweat?" with the following options: 
- heat produced
 - The body's fuel
 - a gas in the air
 - hydration
 - When the water is hot
 - air cools
 - matter vibrating
 - Cooling vapors


 

  The body's fuel       