In an embryo sac, the cells that degenerate after fertilisation are

Options

A. synergids and primary endosperm cell
B. synergids and antipodals
C. antipodals and primary endosperm cell
D. egg and antipodals

Answer

To answer the question regarding which cells in an embryo sac degenerate after fertilization, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Embryo Sac**: The embryo sac is a structure within the ovule of flowering plants that contains the female gametes. It typically consists of several types of cells, including the egg cell, synergids, antipodals, and the central cell.

2. **Identifying the Cells**: In the embryo sac, the key cells are:
- **Egg Cell**: The female gamete that fuses with the male gamete (sperm).
- **Synergids**: Two cells located near the egg cell that help in guiding the pollen tube for fertilization.
- **Antipodal Cells**: Three cells located at the opposite end of the embryo sac that do not play a direct role in fertilization.
- **Central Cell**: Contains two polar nuclei and develops into the endosperm after fertilization.

3. **Process of Fertilization**: When fertilization occurs, the male gamete fuses with the egg cell to form a zygote. The central cell also fuses with another male gamete to form the triploid endosperm.

4. **Degeneration of Cells**: After fertilization, certain cells in the embryo sac do not have a role in the development of the embryo or the endosperm and thus degenerate. Specifically:
- **Synergids**: These cells help in the fertilization process but degenerate after the sperm enters the egg cell.
- **Antipodal Cells**: These cells do not contribute to the formation of the embryo or endosperm and also degenerate after fertilization.

5. **Conclusion**: The cells that degenerate after fertilization in the embryo sac are the synergids and antipodal cells.

### Final Answer:
The cells that degenerate after fertilization in an embryo sac are **synergids and antipodal cells**.

---