You are presented with the question "What is lung cancer most often caused by?" and the following answer choices: 
- the Moon
 - Pollution
 - sunlight
 - Chemical energy
 - fossil fuels
 - cigarettes
 - burning
 - marijuana smoke

Now knowing that lung cancer is most often caused by exposure to tobacco smoke and tobacco is smoked in pipes or in cigarettes or bidis, choose the best answer.


 

      cigarettes   