Which of the following factors have not led to the recovery of the plains bison gene pool?

a. prolific reproduction

b. interbreeding with cattle

c. 100 member founding population

d. human conservation efforts

The 100 member founding population is known to be one of the causes of the plains bison gene pool being hindered. It's due to the founding and renovation of the fields around the world due to human efforts, as well as hunting them down which caused to diminish them, which became the very reason why it stopped recovering for good. Therefore the answer is C.