Fact 1: Evolution is a change in the characteristics of living things over time.

Fact 2: An organism is a living thing.

Given the two facts above, answer the question "evolution is the change in characteristics of what over time?" with the following options: 
- gravity
 - animals
 - vegetation
 - h2o
 - density
 - organisms
 - alleles
 - humans


 

      organisms   