Which of the following best describes how a biotic factor can limit the population growth in a species?

Question

A sudden drop in temperature causes nearly half of the species' population to die.
A parasite invades the species and causes its population to decline.
Disease leads to a decline in the reproductive rate of the species' main predator.
Lack of rainfall over a long period of time forces the species to migrate to a new location.

Answer 1

A parasite invades the species and causes its population to decline.