Conservation Biologists Are Often Concerned That When the Population Size

Conservation biologists are often concerned that when the population size of an endangered species becomes too small it is at risk of extinction for which reason?

A) They can no longer evolve.
B) Their rate of breeding will decline.
C) They may be more susceptible to changes in the environment or disease.
D) They are at risk of sympatric isolation.
E) They are at risk of developing prezygotic barriers to reproduction.