In diagram the sheath which covers plumule is shown by :

The correct answer is Option (1) → A

The plumule (shoot apex with leaf primordia) is enclosed in a hollow sheath, the coleoptile. In the figure it is A, the curved sheath at the top of the embryo.

Option (1) A — Correct. In the grass embryo, the shoot apex and leaf primordia (plumule) are enclosed in a hollow foliar structure, the coleoptile. In the figure, the coleoptile is A.

Option (2) B — Incorrect. B is the shoot apex and leaf primordia inside the sheath.

Option (3) C — Incorrect. C is a part of the embryonal axis, not a sheath.

Option (4) D — Incorrect. D is the coleorhiza, the sheath over the radicle.

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.”