Fact 1: Most carcinogens cause cancer by producing mutations in DNA.

Fact 2: Lung cancer is the deadliest of all cancers.

Given the two facts above, answer the question "what cause production of mutations in DNA of areas such as lungs" with the following options: 
- Damages them
 - the environment
 - carcinogens
 - cigarettes
 - rays or beams
 - smoking tobacco
 - smoking
 - Pollution


 

   carcinogens      