Structure of testing chemical nature of water entering mantle cavity through inhalent siphon

Options

A. Statocyst
B. Organ of Bojanus
C. ospharidium
D. Statolith

Answer

To determine the structure responsible for testing the chemical nature of water entering the mantle cavity through the inhalant siphon, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for the structure that tests the chemical nature of water entering the mantle cavity through the inhalant siphon.

2. **Understand the Options**: The options provided are:
- A) Stethosist
- B) Organ of Bojanus
- C) Ospheridium
- D) Statolith

3. **Analyze Each Option**:
- **Stethosist**: This is not a recognized biological structure related to water testing; it seems to be a misnomer.
- **Organ of Bojanus**: This is an excretory organ found in mollusks, not directly involved in testing water.
- **Statolith**: These are structures involved in balance and orientation in invertebrates, not related to chemical testing.
- **Ospheridium**: This is a sensory organ found in some mollusks, specifically associated with the gills. It is involved in detecting the chemical composition of the water, particularly for olfactory (smell) purposes.

4. **Conclusion**: Based on the analysis, the structure that tests the chemical nature of water entering the mantle cavity is **Ospheridium**.

5. **Final Answer**: The correct answer is **C) Ospheridium**.