Pollen grain is

Options

A. highly reduced male gametophyte
B. well developed male gametophyte
C. highly reduced sporophyte
D. well developed female gametophyte

Answer

To answer the question "Pollen grain is," we need to analyze the options provided and understand the characteristics of pollen grains in the context of plant biology.

### Step-by-Step Solution:

1. **Understanding Pollen Grain**:
- Pollen grains are the male gametophytes in seed-bearing plants. They are crucial for reproduction as they carry male gametes.

2. **Identifying the Structure**:
- Pollen grains are highly reduced structures. They typically consist of just a few cells, often only two or three.

3. **Formation of Pollen Grain**:
- Pollen grains develop from microspores, which are produced in the male reproductive structures (anthers) of flowering plants (angiosperms).

4. **Function of Pollen Grain**:
- The primary function of pollen grains is to facilitate fertilization. They are transferred from the anther to the stigma of a flower through various means such as wind, water, or insects, in a process known as pollination.

5. **Comparison with Other Options**:
- The other options provided (well-developed male gametophyte, highly reduced sporophyte, well-developed female gametophyte) do not accurately describe pollen grains.
- A well-developed male gametophyte would imply a more complex structure than what pollen grains represent.
- A highly reduced sporophyte is incorrect as pollen grains are not sporophytes but gametophytes.
- The term "well-developed female gametophyte" refers to the embryo sac, which is not related to pollen grains.

6. **Conclusion**:
- Based on the analysis, the correct answer is that pollen grain is a **highly reduced male gametophyte**.

### Final Answer:
Pollen grain is a **highly reduced male gametophyte**.

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