The correct option is D Triticum
Cotyledons does not form first pair of leaves in Triticum. Its the scutellum which arises first. The scutellum is part of the structure of a barley and rice seed, the modified seed leaf. The scutellum can also refer to the equivalence of a thin cotyledon in monocots. It is very thin with high surface area and serves to absorb nutrients from the endosperm during germination.
Thus, the correct answer is option D.