In nature, cleistogamous flowers are

Options

A. Wind-pollinated
B. Bird-pollinated
C. Self-pollinated
D. Insect-pollinated

Explanation

### Step-by-Step Solution:

1. **Understanding Cleistogamous Flowers**:
- Cleistogamous flowers are a type of flower that undergoes self-pollination. This means that the reproductive structures (anthers and stigma) are located on the same flower and do not open to the outside environment.

2. **Characteristics of Cleistogamous Flowers**:
- In cleistogamous flowers, the anthers and stigma remain closed and hidden. This prevents exposure to external pollinators and ensures that pollination occurs internally.

3. **Analyzing the Options**:
- **Option A: Wind Pollinated**:
- Cleistogamous flowers do not rely on wind for pollination, so this option is incorrect.
- **Option B: Bird Pollinated**:
- These flowers are not pollinated by birds. Bird-pollinated flowers are known as ornithophilous flowers, making this option also incorrect.
- **Option C: Self Pollinated**:
- This is the correct option. Cleistogamous flowers are indeed self-pollinated due to their closed structure that facilitates non-opening self-pollination.
- **Option D: Insect Pollinated**:
- Cleistogamous flowers do not depend on insects for pollination. Insect-pollinated flowers are referred to as entomophilous flowers, so this option is incorrect as well.

4. **Conclusion**:
- The only correct option is **C: Self Pollinated**. Cleistogamous flowers are characterized by their ability to self-pollinate due to their closed reproductive structures.