The correct option is
B Poaceae
Caryopsis is a dry one-seeded fruit in which the ovary wall is united with the seed coat and fused into a single unit. It is a type of simple dry fruit which is monocarpellate (formed from a single carpel), indehiscent (not opening at maturity). The caryopsis is commonly called grain and caryopsis fruit is characteristic of family Poaceae.
So, the correct answer is 'Poaceae'.