You are presented with the question "What could cause lenses to fog?" and the following answer choices: 
- energy of moving objects
 - Transpiration from plants
 - Water evaporating
 - heating liquids
 - Water vapor cooling
 - Ice sublimating
 - scattered light
 - The atmosphere

Now knowing that water vapor cooling causes that water vapor to condense and all lenses are anti-fog coated to eliminate condensation, choose the best answer.


 

     Water vapor cooling    