Question

The organisms of population and population B are now in capable of interbreeding and producing Offspring which biological process most likely caused the situation to occur

Answer 1

Natural selection.

Step-by-step explanation:

Natural Selection:

Natural selection is the evolution's one of the basic mechanism in which phenotypic variant individuals or organisms survive or reproduce with change in the heritable traits in a population over generations. With the passage of time, this process help the organisms to adapt their environment.

So, the population A and population B organisms interbreed and produce offspring with the process of natural selection.