Length of pollen tube depends on the distance between

Options

A. pollen grain and upper surface of stigma
B. pollen grain on upper surface of stigma and ovule
C. pollen grain in anther and upper surface of stigma
D. upper surface of stigma and lower part of style

Explanation

### Step-by-Step Solution

1. **Understanding Pollination**: Pollination is the process where pollen grains are transferred from the anther (the male part of the flower) to the stigma (the female part of the flower).

2. **Structure of the Female Reproductive Part**: The female reproductive part of a flower consists of three main parts:
- **Stigma**: The part where pollen grains land.
- **Style**: The tube that connects the stigma to the ovary.
- **Ovary**: The part where fertilization occurs.

3. **Pollen Tube Formation**: After pollination, when pollen grains land on the stigma, a pollen tube begins to grow. This tube carries the male gamete (sperm) down to the ovary for fertilization.

4. **Length of the Pollen Tube**: The length of the pollen tube is determined by the distance it needs to travel from the stigma to the ovary. Specifically, it depends on:
- The upper surface of the stigma (where the pollen grain lands).
- The lower surface of the style (which connects the stigma to the ovary).

5. **Conclusion**: Therefore, the length of the pollen tube depends on the distance between the upper surface of the stigma and the lower surface of the style.

6. **Correct Answer**: The correct option is that the length of the pollen tube depends on the distance between the upper surface of the stigma and the lower surface of the style.