Fact 1: Harming an animal species has a negative impact on the population size of that species.

Fact 2: People understand that habitat destruction and pollution are harmful to wildlife.

Given the two facts above, answer the question "What has a negative impact on a species population size?" with the following options: 
- influenza
 - assistance
 - pollution
 - distractions
 - liver cancer
 - copper
 - Pesticides
 - disease


 

   pollution      