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

Fact 2: Ecology is the study of populations or communities.

Given the two facts above, answer the question "Ecology studies something that decreases when an animal species is what?" with the following options: 
- omnivores
 - harmed
 - deadly
 - dead
 - haploid
 - negative
 - dormant
 - inactive


 

  harmed       