Answer:
The correct answer would be A) mechanical.
Mechanical reproductive isolation is a type of reproductive isolation in which morphological changes prevent successful mating or pollination.
Difference in structure or complementary nature of genitalia prevent the successful mating.
In plants, difference in structure of flower prevents the successful pollination.
In addition, plants achieve mechanical reproductive isolation by attracting different type of pollinators due to which pollination does not occur between different species.
