If we break down the word autotroph, auto means “self” and troph means "feeding" or nourishment. However, when we break the word heterotroph, we get hetero- meaning other, and troph meaning feeders.
This is the critical difference between these two groups. Autotrophs synthesize or make their own food whereas, heterotrophs cannot make their own food thus have to rely on others by eating or absorbing others. For example, plants are autotrophs because they can make their own food using photosynthesis, whereas, humans are heterotrophs because we have to eat others to survive.
"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.
