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 is the most likely explanation for this periodic cycling of the disease? a. New coyotes, which are susceptible to the disease, 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 infected slowly falls as they recover.
d. Coyotes from other populations who have already been infected and recovered from the disease immigrate into the study population.