After pollination which of the following events is crucial for fertilization to occurs in flowering plants ?

Options

A. Sperm swim to the egg and the polar nuclei
B. Petals close around the reproductive parts
C. Meiosis occurs within the pollen grain
D. A pollen tube grows from the stigma to the ovule

Answer

To answer the question regarding the crucial event for fertilization to occur in flowering plants after pollination, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Pollination**:
- Pollination is the process where pollen grains are transferred from the male anther of a flower to the female stigma. This is the first step in the fertilization process.

2. **Identifying the Need for Fertilization**:
- After pollination, fertilization is required for the formation of seeds. Fertilization involves the fusion of male and female gametes (sperm and egg).

3. **Evaluating the Options**:
- **Option A**: "Sperms swim to the egg and the polar nuclei."
- This is incorrect because in flowering plants, sperm does not swim; instead, it travels through the pollen tube.
- **Option B**: "Petals close around the reproductive parts."
- This is also incorrect as petals primarily serve to attract pollinators and do not play a direct role in fertilization.
- **Option C**: "Meiosis occurs within the pollen grain."
- This is incorrect because meiosis occurs before pollination to produce microspores that develop into pollen grains.
- **Option D**: "A pollen tube grows from the stigma to the ovule."
- This is the correct answer. After pollination, the pollen grain germinates on the stigma, forming a pollen tube that grows down to the ovule, allowing the sperm to reach the egg for fertilization.

4. **Conclusion**:
- The crucial event for fertilization to occur after pollination in flowering plants is the growth of the pollen tube from the stigma to the ovule.

### Final Answer:
The crucial event for fertilization to occur after pollination in flowering plants is **"a pollen tube grows from the stigma to the ovule."**

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