The correct option is C Caryopsis
The most evolved is caryopsis, the single seeded fruit of Poaceae. A caryopsis is a type of simple dry fruit that is monocarpellate and indehiscent and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed coat. The caryopsis is popularly called as a grain and is the fruit typical of the family Poaceae (or Gramineae), which includes wheat, rice, and corn. The term grain is also used in a more general sense as synonymous with cereal. Considering that the fruit wall and the seed are intimately fused into a single unit and the caryopsis or grain is a dry fruit, little concern is given to technically separating the terms fruit and seed in these plant structures.
Therefore, the correct answer is option C.