Fact 1: Mutations that lead to cancer usually occur in genes that control the cell cycle.

Fact 2: Cancer is an example of a mutation in cells.

Given the two facts above, answer the question "What usually occur in genes that control the cell cycle?" with the following options: 
- Leptospirosis
 - competition
 - A Greek letter
 - a mutation in cells
 - Plant reproduction
 - biological diversity
 - resistance
 - resistance activities


 

    a mutation in cells     