You are presented with the question "What does the skin protect against?" and the following answer choices: 
- smallpox
 - A virus
 - disease
 - sun's heat
 - cancer
 - leukemia
 - Pollution
 - heat energy

Now knowing that skin is used for protecting the body from harmful substances and pollution is the release of harmful substances into the environment, choose the best answer.


 

       Pollution  