Which one of the following is an example of cleistogamy ?

Options

A. Sunflower
B. Vallisneria
C. Viola
D. Calatropis

Answer

To solve the question "Which one of the following is an example of cleistogamy?", we need to understand the concept of cleistogamy and identify which of the given options fits this definition.

### Step-by-Step Solution:

1. **Understand Cleistogamy**: Cleistogamy refers to a type of self-pollination that occurs in closed flowers. In cleistogamous flowers, the reproductive organs are enclosed within the flower, preventing cross-pollination with other flowers.

2. **Identify the Options**: The options provided are:
- A. Sunflower
- B. Vasculinaria
- C. Viola
- D. Keratopis

3. **Analyze Each Option**:
- **A. Sunflower**: Sunflowers are known for their open flowers and typically undergo cross-pollination. This does not fit the definition of cleistogamy.
- **B. Vasculinaria**: This is not a commonly recognized example of cleistogamy.
- **C. Viola**: Viola species (like violets) are known to produce both open flowers (for cross-pollination) and closed flowers (for self-pollination), making them a classic example of cleistogamy.
- **D. Keratopis**: This is not a widely recognized example of cleistogamy.

4. **Conclusion**: Based on the analysis, the only option that fits the definition of cleistogamy is **C. Viola**.

### Final Answer:
C. Viola