Which of the following is not a pre-fertilization event in flowering plants ?

Options

A. Microgametogenesis
B. Megagametogenesis
C. Pollination
D. Double fertilisation

Answer

To determine which of the following is not a pre-fertilization event in flowering plants, we will analyze each option provided:

1. **Microgametogenesis**: This is the process of formation of male gametes (pollen grains) in flowering plants. It occurs before fertilization as it involves the development of the male gametes that will participate in fertilization.

2. **Megagametogenesis**: This refers to the formation of female gametes (embryo sac) in flowering plants. Similar to microgametogenesis, this process also occurs prior to fertilization, as it prepares the female gametes for the fusion with male gametes.

3. **Pollination**: This is the transfer of pollen grains (male gametes) from the anther to the stigma of a flower. Pollination is a crucial event that occurs before fertilization, as it brings the male and female gametes together for fertilization to occur.

4. **Double fertilization**: This is a unique event in flowering plants where one male gamete fertilizes the egg cell to form the zygote, and another male gamete fuses with two polar nuclei to form the triploid endosperm. This process occurs after the male and female gametes have fused, making it a post-fertilization event.

**Conclusion**: The event that is not a pre-fertilization event in flowering plants is **double fertilization**.

### Step-by-Step Solution:
1. **Identify the processes involved in fertilization**: Understand what constitutes pre-fertilization events (gamete formation and transfer).
2. **Analyze each option**: Evaluate whether each option occurs before fertilization.
3. **Determine the odd one out**: Identify which process does not fit the criteria of a pre-fertilization event.
4. **Conclude the answer**: Confirm that double fertilization is the correct answer as it occurs after fertilization.