In 1987, 18 black-footed ferrets, the last known individuals of this species, were captured and brought into a captive breeding
program in Wyoming. In 1989, the total ferret population, still in captivity, was 120 animals. These 120 animals in 1989 represented: A) N, the total population size.B) ∆N, the change in population size from 1987 to 1989.C) ∆N/∆t, the rate of change in population size.D) r, the per capita change in population size.E) r, the exponential rate of growth of the population.
