Swollen spongy petiole is present in

Options

A. Hydrilla
B. Eichhornia
C. Ruppia
D. Pistia.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism has a swollen spongy petiole. We need to identify the correct option from the given choices.

2. **Analyzing the Options**:
- **Option 1: Hydrilla**: This is a submerged aquatic plant and does not have a swollen spongy petiole.
- **Option 2: Ecornea (Eichhornia)**: This is a free-floating aquatic plant known for its swollen spongy petiole that aids in buoyancy.
- **Option 3: Rupia**: This is also an aquatic plant, but it does not have a swollen spongy petiole.
- **Option 4: Pistia**: Similar to Hydrilla and Rupia, it does not possess a swollen spongy petiole.

3. **Identifying the Correct Answer**: Among the options, Ecornea (Eichhornia) is the only plant that has a swollen spongy petiole, which contains air cavities that provide buoyancy, allowing it to float freely on water.

4. **Conclusion**: The correct answer is **Option 2: Ecornea (Eichhornia)**.

---