In the wheat grain, the embryo contains a single large cotyledon that…

The correct answer is Option (2) → scutellum

Embryos of monocotyledons have only one cotyledon. In the grass family, to which wheat belongs, this single cotyledon is called the scutellum. It lies towards one side (lateral) of the embryonal axis.

Option (1) coleoptile — Incorrect. The coleoptile is the hollow foliar structure that encloses the shoot apex and a few leaf primordia. It is not the cotyledon.

Option (2) scutellum — Correct. The scutellum is the cotyledon of the grass embryo, situated on one side of the embryonal axis.

Option (3) coleorhiza — Incorrect. The coleorhiza is the undifferentiated sheath that encloses the radicle and root cap at the lower end of the axis.

Option (4) epiblast — Incorrect. The epiblast is a separate small part labelled in the NCERT figure of a grass embryo (Figure 1.14b). The label for the cotyledon in that figure is the scutellum.

NCERT Extract:
Embryo – “Embryos of monocotyledons (Figure 1.14 b) possess only one cotyledon. In the grass family the cotyledon is called scutellum that is situated towards one side (lateral) of the embryonal axis. At its lower end, the embryonal axis has the radical and root cap enclosed in an undifferentiated sheath called coleorrhiza. The portion of the embryonal axis above the level of attachment of scutellum is the epicotyl. Epicotyl has a shoot apex and a few leaf primordia enclosed in a hollow foliar structure, the coleoptile.”