Study the diagram given below

In the given diagram showing the carpel of an insect pollinated flower, the most likely reason for the non-germination of pollen grain Z is:

Options

A. Pollen grains X and Y were brought to the stigma earlier, therefore, their germination inhibited the germination of pollen grain Z.
B. Pollen grain Z was brought to the flower by wind, while pollen grains X and Y were brought to the flower by insects.
C. Pollen grain Z lacks protrusions that allow it to adhere properly onto the stigma surface.
D. Pollen grain Z comes from a flower of an incompatible species.

Answer

D

Explanation

Pollen grains can only germinate if the pollen grain and stigma are compatible, i.e., of the same or closely related species, Pollen grains X and Y must have come from a compatible species. Only compatible pollen grains germinate and form pollen tubes.