Reproductive isolation occurs when?
a. a small number of individuals moves and starts a new population
b. some catastrophic event greatly reduces the size of a population
c. the gene pools of different populations have become very diversified
d. members of different populations can no longer mate successfully

I would say D. Members of different populations can no longer mate successfully. I hope I'm right and good luck :)

The answer is D: members of a different populations can no longer mate successfully

Or if they do reproduce their offspring will be sterile meaning their offspring won't be able to reproduce. An example would be a horse and a donkey mating. They usually produce sterile offspring.

Hopefully this helped and good luck.

The basic repeating unit of nucleic acids are known as nucleotides. a nucleotide consists of three distinct chemical groups.