Which of the following is not correct?

Options

A. The megaspore mother cell is differentiated from one of the cells of the nucleus.
B. The megaspore mother cell divides meiotically to form four megaspores.
C. One of the megaspores enclosed within the megasporangium develops into a multicellular female gametophyte.
D. The multicellular female gametophyte is not retained within the megasporangium

Answer

To solve the question, "Which of the following is not correct?" we will analyze each of the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Megaspore Mother Cells**:
- The megaspore mother cells (also known as megasporocytes) are diploid cells that undergo meiosis to produce haploid megaspores.
- **Hint**: Recall that megasporocytes are diploid and undergo meiosis.

2. **Analyzing Option 1**:
- Option 1 states that megaspore mother cells are differentiated from one cell. This is correct because they arise from a single diploid cell that undergoes meiosis.
- **Hint**: Think about the origin of megaspore mother cells.

3. **Analyzing Option 2**:
- Option 2 claims that megaspore mother cells meiotically divide to form four megaspores. This is also correct as meiosis of the megaspore mother cell results in four haploid megaspores.
- **Hint**: Remember the process of meiosis and its outcome.

4. **Analyzing Option 3**:
- Option 3 states that one of the megaspores is enclosed in the megasporangium and develops into a multicellular female gametophyte. This is true because the surviving megaspore develops into the female gametophyte within the megasporangium.
- **Hint**: Consider the fate of the megaspores after meiosis.

5. **Analyzing Option 4**:
- Option 4 claims that the multicellular female gametophyte is not retained in the megasporangium. This statement is incorrect because the multicellular female gametophyte is indeed retained within the megasporangium during its development.
- **Hint**: Think about where the female gametophyte develops.

### Conclusion:
After analyzing all the options, we find that **Option 4** is the statement that is not correct. The multicellular female gametophyte is retained in the megasporangium.

### Final Answer:
**Option 4** is the correct answer as it is the statement that is not correct.