Fact 1: Harming an animal species causes that animal 's population to decrease.

Fact 2: Species are the different kinds of organisms.

Given the two facts above, answer the question "Harming a certain kind of animal will cause the population of that animal to do what?" with the following options: 
- decrease
 - eat more
 - increase
 - break off
 - threatened
 - reproduce
 - reduce
 - kill them


 

 decrease        