Contrivance for self pollination/autogamy is

Options

A. Homogamy
B. Bisexuality
C. Cleistogamy
D. All

Answer

### Step-by-Step Solution

1. **Understanding Self-Pollination**: Self-pollination, or autogamy, is the process where pollen from the male part of a flower fertilizes the female part of the same flower or another flower on the same plant.

2. **Types of Self-Pollination**: There are two main types of self-pollination:
- **Autogamy**: Pollen transfer occurs within the same flower.
- **Geitonogamy**: Pollen transfer occurs between different flowers of the same plant.

3. **Contrivances for Autogamy**: Several adaptations or contrivances help facilitate self-pollination:
- **Bisexual Flowers**: Flowers must have both male (stamens) and female (pistils) reproductive organs.
- **Homogamy**: This means that the male and female reproductive organs mature at the same time, allowing for effective self-pollination.
- **Closed Flowers**: Flowers that remain closed can promote self-pollination by preventing pollen from being dispersed to other plants.
- **Bud Pollination**: Pollination can also occur when flowers are still in bud form, which helps in self-pollination.

4. **Evaluating the Options**: The question provides four options:
- 1. Homogamy
- 2. Bisexuality
- 3. Calistogamy (a type of self-pollination where flowers remain closed)
- 4. All of the above

5. **Conclusion**: Since all the mentioned factors (homogamy, bisexuality, and calistogamy) contribute to self-pollination, the correct answer is option 4: all of these.