"Mechanical" would be the kind of reproductive isolation among the choices given in the question that has been observed in these two species. The correct option among all the options that are given in the question is the first option or option "A". I hope that the answer has come to your help.
<span>The correct answer is ‘gametes’. Gametes are sex cells: male gametes are sperm cells and female gametes are egg cells. Gametes each contain one set of chromosomes, and when fertilisation occurs, they form a diploid cell.</span>
