Molluscans test the quality of water with the help of

Options

A. statocyst
B. tentacles
C. osphradium
D. ctenidia

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks how molluscans test the quality of water. We need to identify the correct anatomical structure or organ responsible for this function.

2. **Analyzing the Options**: The options provided are:
- Statocysts
- Tentacles
- Osphradium
- Ctenidia

3. **Evaluating Statocysts**: Statocysts are sensory organs that help in balance and orientation in water. They do not play a role in testing water quality. Therefore, this option is incorrect.

4. **Evaluating Tentacles**: Tentacles in molluscs are primarily sensory and assist in capturing food. While they have sensory functions, they do not specifically test water quality. Hence, this option is also incorrect.

5. **Evaluating Ctenidia**: Ctenidia are gill-like structures in molluscs that are involved in respiration. They facilitate gas exchange but do not test water quality. Thus, this option is incorrect as well.

6. **Evaluating Osphradium**: The osphradium is a chemosensory organ found in many molluscs. It is specifically adapted to sample the surrounding water and assess its quality. This makes osphradium the correct answer to the question.

7. **Conclusion**: Based on the analysis, the correct answer is that molluscans test the quality of water with the help of the osphradium.

**Final Answer**: Molluscans test the quality of water with the help of the osphradium.

---