Fact 1: Cells that divide uncontrollably may form a tumor, or abnormal mass of cells.

Fact 2: For example, a fibroid is a tumor, a wart is a tumor, and cancers are tumors.

Given the two facts above, answer the question "When cells start to divide uncontrollablly, they may form a what?" with the following options: 
- anemia
 - tissue
 - fever
 - cell
 - organ
 - fibroid
 - acid rain
 - illness


 

      fibroid   