The process by which members of isolated populations become so different in genetic makeup that they cannot produce live, fertile offspring if they are rejoined together is best described as

The answer is reproductive isolation.

Explanation:

Reproductive isolation is a series of mechanisms that prevent different species from reproducing. This may occur before fertilization (the species cannot produce offspring) or after it (the offspring becomes sterile).

Some examples of these mechanisms are different mating rituals or variability of sexual organs, making species "unfit" to copulate.

world bank is the correct answer.