Fact 1: Mutations are essential for evolution to occur.

Fact 2: Mutations Mutations are caused by random changes in genes.

Given the two facts above, answer the question "what is essential for evolution to occur?" with the following options: 
- random changes in genes
 - that material's properties
 - cancer
 - remains of prehistoric life
 - h2o
 - Plant reproduction
 - revolutions
 - the environment


 

 random changes in genes        