Name the part of gynoecium that determines the compatible nature of pollen grain.

Explanation

**Step-by-Step Solution:**

1. **Understanding Gynoecium**: The gynoecium is the female reproductive part of a flowering plant. It consists of structures that are essential for reproduction.

2. **Identifying Gynoecium Components**: The gynoecium is made up of three main parts:
- **Stigma**: The top part that receives pollen.
- **Style**: The elongated part that connects the stigma to the ovary.
- **Ovary**: The swollen base that contains ovules.
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