The correct option is
D Pea nut
Geocarpy is an extremely rare means of plant reproduction in which plants produce diaspores within the soil. This may occur with subterranean flowers , or from aerial flowers, which penetrate the soil after flowering . It has evolved as an effective means of ensuring a suitable environment for the plant's offspring. Geocarpic fruit is a peanut. Geocarpic means producing or ripening the fruit beneath the surface of the ground like the peanuts.
So the correct answer is 'Pea nut'.