Megasporogenesis happens in.......................

Options

A. Exine layer.
B. Nucellus
C. Tapetum
D. Both (a) and (b)

Explanation

**Step-by-Step Solution:**

1. **Understanding Megasporogenesis**: Megasporogenesis is the process of formation of megaspores from a megaspore mother cell (megaspore mother cell is diploid).

2. **Location of Megasporogenesis**: This process occurs within the ovule of seed plants, specifically in the nucleus of the ovule.

3. **Role of the Megaspore Mother Cell**: The megaspore mother cell, which is diploid (2N), undergoes meiosis to produce haploid (1N) megaspores.

4. **Outcome of Meiosis**: The meiosis of the megaspore mother cell results in the formation of four haploid megaspores. However, typically, only one of these megaspores survives to develop into the female gametophyte.

5. **Conclusion**: Therefore, the correct answer to the question "Megasporogenesis happens in..." is the nucleus of the ovule.

**Final Answer**: Megasporogenesis happens in the nucleus of the ovule.

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