The correct option is C scutellum
Cotyledon is an embryonic leaf seen in germinating seeds. It is called scutellum in monocots such as grasses.
The radicle is the root tip of the embryo with is covered with a root cap. The radicle and the root cap is enclosed in a sheath called coleorrhiza.
The plumule or stem tip is enclosed in a sheath called coleoptile.