The functional megaspore referred to as :

Options

A. The megaspore that degenerates after formation.
B. The megaspore that only develops in female gametophyte .
C. The megaspore that undergoes reduction division.
D. The megaspore that is functionally inactive.

Answer

To solve the question regarding the functional megaspore, we will analyze the options provided and determine which one correctly defines a functional megaspore.

### Step-by-Step Solution:

1. **Understanding Functional Megaspores**:
- Functional megaspores are the megaspores that develop into female gametophytes and are capable of producing gametes (ovules).

2. **Analyzing the Options**:
- **Option A**: "The megaspore that degenerates after formation."
- This option describes an accessory megaspore, which is not functional. Therefore, this is incorrect.

- **Option B**: "The megaspore that only develops in female gametophyte."
- This option is correct. Functional megaspores are indeed those that develop into female gametophytes and are involved in gamete production.

- **Option C**: "The functional megaspore that undergoes reduction division."
- This option is incorrect because functional megaspores are haploid and do not undergo reduction division (meiosis). They develop directly into gametophytes.

- **Option D**: "The megaspore that is functionally inactive."
- This option is also incorrect. Functional megaspores are active and contribute to the formation of gametes.

3. **Conclusion**:
- The only option that accurately describes a functional megaspore is **Option B**: "The megaspore that only develops in female gametophyte."

### Final Answer:
The functional megaspore is referred to as the megaspore that only develops in female gametophyte.

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