Self - incompatibility is

Options

A. the production of unisexual flowers
B. a genetic mechanism which prevents self pollen from fertilizing the ovules
C. an ecological mechanism which prevents self pollen from fertilizing the ovules
D. production of male and female flowers on different plants

Answer

### Step-by-Step Solution:

1. **Definition of Self-Incompatibility**: Self-incompatibility is a genetic mechanism in flowering plants that prevents self-pollen from fertilizing the ovules of the same plant. This mechanism is crucial for promoting genetic diversity.

2. **Mechanism of Action**: This mechanism works by preventing pollen grains from one flower of a plant from fertilizing the ovules of another flower on the same plant. It ensures that fertilization occurs only between different plants, thereby promoting outcrossing.

3. **Types of Flowers**: In many cases, self-incompatibility is associated with the production of unisexual flowers. This means that a plant may produce either male or female flowers, but not both, which further reduces the chances of self-fertilization.

4. **Ecological Aspect**: While self-incompatibility is primarily a genetic mechanism, it can also have ecological implications. For example, it can lead to the production of male and female flowers on different plants, which encourages cross-pollination.

5. **Importance in Plant Families**: Self-incompatibility is commonly observed in certain plant families, such as the Solanaceae family. This family includes many important crops and ornamental plants.

6. **Benefits of Self-Incompatibility**: The primary benefit of self-incompatibility is that it prevents inbreeding, which can lead to a reduction in genetic diversity and increased vulnerability to diseases. By promoting outcrossing, plants can maintain healthier populations.