In which of the following aquatic plant flowers are borne inside water but pollination occurs at the surface of water ?

Options

A. Ceratophyllum
B. Eicchornia
C. Vallisneria
D. Utricularia

Answer

To determine which aquatic plant has flowers that are borne underwater but pollination occurs at the surface of the water, we can analyze the options given: Stratophyllum, Eichhornia, Vallisneria, and Eutricholaria.

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify an aquatic plant where the flowers are submerged in water, but the actual process of pollination occurs at the water's surface.

2. **Analyzing Each Option**:
- **Stratophyllum**: The flowers of this plant are submerged underwater, and pollination occurs underwater as well. This does not meet the criteria.
- **Eichhornia**: The flowers of this plant are above the water surface, and pollination occurs through insects and wind. This does not meet the criteria since the flowers are not submerged.
- **Vallisneria**: The flowers of Vallisneria are indeed submerged underwater, and pollination occurs at the surface of the water. This meets both conditions.
- **Eutricholaria**: The flowers of this plant are also submerged, but the pollination mechanism is not specified as occurring at the surface; it may vary.

3. **Conclusion**: Based on the analysis, Vallisneria is the only plant that has submerged flowers and pollination that occurs at the surface of the water.

### Final Answer:
The correct answer is **Vallisneria**.