[I'm not to sure. I think it's c.]
What group of organisms are most in danger of extinction?
a.those with small populations
b.those that migrate or need special habitats
c.those with large populations that breed quickly
d.both (a) and (b)
Nuts to c, if the population is large, and it can reproduce quickly, who would think it is going to collapse.
Ducks need feeding places along their migration routes...
a and b are good answers.