In the dicot embryo, the cotyledons and plumule are derived from

The correct option is B epibasal cells
In dicots, the zygote divides transversely to form a terminal (apical) cell and a basal cell. The terminal cell is termed the embryo cell. The larger basal cell is called the suspensor cell.

The first cell of the suspensor towards the micropylar end (the micropyle is the aperture in the ovule through which the pollen tube enters) becomes swollen and functions as haustorium.

The last cell of the suspensor at the end adjacent to the embryo is known as hypophysis. Hypophysis gives rise to the radicle and the root cap. The embryo cell undergoes two vertical divisions to give rise to the quadrant stage. This quadrant further undergoes one transverse division to form eight cells (octant stage) arranged in two tiers- epibasal cell (near the terminal) and hypobasal (near the suspensor).

The epibasal cells eventually give rise to the two cotyledons and the plumule. The hypobasal cells produce the hypocotyl except for its tip.