You are presented with the question "Riding a bike reduces what?" and the following answer choices: 
- energy usage
 - Greenhouse gasses
 - acid rain
 - harmful substances
 - Greenhouse gases
 - temperature
 - prolactin release
 - storms

Now knowing that riding a bike does not cause pollution and city employees use bicycles on the job to save energy and reduce air pollution, choose the best answer.


 

 energy usage        