Question

You are studying a population of wild coyotes and notice that every three years there is an epidemic of a bacterial disease. Which of the following best explains this periodic cycling of the disease?
a) New coyotes are continuously born into the population.
b) Coyotes are dying from other causes over time.
c) During an outbreak, the proportion of coyotes who are sick with the disease slowly falls as they recover.
d) Coyotes from other populations, who have already caught and recovered from the disease, immigrate into the study population.

Answer 1

I think the answer would have to be D.
The reason I think that this would have to be the answer is because Coyotes from different populations would have encountered disease and most likely grow immune to them (the ones that survived) ad those coyotes could migrate to the other population of coyotes and those coyotes would get that disease.