What is usually harmful to the population size of a species?
Pollution reproduction viruses disease habitat ecosystems influenza deforestation
A B C D E F G H
Pollution is usually harmful to one or more species of animal or plant.
Pollution is usually harmful to population size of a species. 
What is usually harmful to the population size of a species? (A) Pollution (B) reproduction (C) viruses (D) disease (E) habitat (F) ecosystems (G) influenza (H) deforestation