Development of an embryo sac from a nucellar cell is

Options

A. Diplospory
B. Apospory
C. Apogamy
D. Adventitive embryony.

Answer

To determine the development of an embryo sac from a nucellar cell, we need to analyze the given options one by one.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- An embryo sac is the female gametophyte in seed plants, which develops from a megaspore.
- Nucellar cells are the cells of the nucellus, which is the central part of the ovule.

2. **Option Analysis**:
- **Option 1: Diplospory**:
- Diplospory is a type of agamospermy where the megaspore mother cell (MMC) undergoes mitosis instead of meiosis to produce an embryo sac.
- Since this does not involve a nucellar cell, this option is incorrect.

- **Option 2: Apospory**:
- Apospory is a type of agamospermy where the nucellar cells divide mitotically to form an unreduced embryo sac.
- This directly involves the development of an embryo sac from a nucellar cell, making this option correct.

- **Option 3: Apogamy**:
- Apogamy refers to the formation of a sporophyte from a gametophyte without the fusion of gametes.
- This does not relate to the development of an embryo sac from a nucellar cell, so this option is incorrect.

- **Option 4: Adventitive Embryony**:
- Adventitive embryony is a type of apomixis where embryos form from sporophytic tissues.
- This does not involve the development of an embryo sac from a nucellar cell, making this option incorrect.

3. **Conclusion**:
- After analyzing all the options, the correct answer is **Apospory**, as it specifically describes the development of an embryo sac from a nucellar cell.

### Final Answer:
The development of an embryo sac from a nucellar cell is known as **Apospory**.