Fact 1: Cancer is a disease in which cells divide out of control.

Fact 2: With specific types of gene damage, the cell starts dividing out of control, forming a tumor.

Given the two facts above, answer the question "Cancer and tumors are a result of specific types of:" with the following options: 
- organs
 - cigarettes
 - radiation
 - layers of fat
 - gene damage
 - rays or beams
 - Chemical energy
 - the skin


 

     gene damage    