Fact 1: Lung cancer is most often caused by exposure to tobacco smoke.

Fact 2: Lung cancer for most is the consequence of smoking.

Given the two facts above, answer the question "What is lung cancer a consequence of?" with the following options: 
- candy cigarettes
 - harmful substances
 - Greenhouse gases
 - malnutrition
 - water vapors
 - metabolic reaction
 - tobacco fumes
 - Pesticides


 

       tobacco fumes  