Please answer the following question: Fact 1: Harming an animal species causes that animal 's population to decrease. Fact 2: Fish are wild animals. Given the two facts above, answer the question "Doing what to fish species causes their population to decrease?" with the following options: - deforestation - repopulating them - Pesticides - hypothyroidism - kill them - harming them - light - helping them
A:
harming them