You are presented with the question "What is NOT a byproduct of using a gasoline engine?" and the following answer choices: 
- chickenpox
 - carbon dioxide
 - carcinogens
 - Collagen
 - water
 - warmth
 - loose dirt
 - uranium

Now knowing that using a gasoline engine requires burning gasoline and for every one gallon of gasoline an engine burns, one gallon of water is produced as a by-product, choose the best answer.


 

        uranium 