Water vapor cooling causes that water vapor to condense, and all lenses are anti-fog coated to eliminate condensation. Given these facts, what could cause lenses to fog among the following options:
- energy of moving objects
 - Transpiration from plants
 - Water evaporating
 - heating liquids
 - Water vapor cooling
 - Ice sublimating
 - scattered light
 - The atmosphere


 

     Water vapor cooling    