The answer is b.In grass family (Gramineae), this cotyledon is called scutellum. It is situated towards lateral side of embryonal axis. This axis at its lower end has radicle and root cap enclosed in a sheath called coleorhiza. The part of axis above the level of attachment of scutellum is called epicotyl.

Plumule- Shoot tip.

Radicle - Embryonic root.

A. Epicotyl- The portion of axis between the plumule and the cotyledonary node.

B. Hypocotyl- The portion of axis between the radicle and the cotyledonary node.

D. Coleoptile- Protective sheath of plumule.

So, the correct answer is 'Epicotyl'

Explanation:
Monocots are a diverse group of flowering plants that have a single embryonic leaf known as cotyledon. The embryonic axis of monocots is composed of various parts that play important roles in the growth and development of the plant. One such part is the epicotyl.

Epicotyl:
The epicotyl is the portion of the embryonic axis of monocots that is located above the point of attachment of the cotyledon or scutellum. It is the region that gives rise to the shoot system of the plant. The epicotyl is also known as the plumule.

Functions of Epicotyl:
Here are some important functions of the epicotyl:

1. Shoot Development: The epicotyl gives rise to the shoot system of the plant, including the stem, leaves, and reproductive structures.

2. Protection: The epicotyl is protected by a sheath called the coleoptile. The coleoptile covers the emerging shoot and protects it from damage as it grows through the soil.

Difference between Hypocotyl and Epicotyl:
The portion of the embryonic axis below the point of attachment of the cotyledon is known as the hypocotyl. The hypocotyl gives rise to the root system of the plant. The main difference between the epicotyl and hypocotyl is that the epicotyl gives rise to the shoot system while the hypocotyl gives rise to the root system.

Conclusion:
In conclusion, the portion of the embryonic axis of monocots above the level of attachment of scutellum is called the epicotyl or plumule. It is an important part of the plant that gives rise to the shoot system and is protected by the coleoptile.