Respiration by gills or pulmonary sac are present in ?

Options

A. Annelida
B. Arthropoda
C. Echinodermata
D. Mollusca

Answer

To determine which group of organisms utilizes gills or pulmonary sacs for respiration, we can analyze the respiratory systems of the given options: annelida, arthropoda, echinodermata, and mollusca.

### Step-by-Step Solution:

1. **Identify the Respiratory System of Annelida:**
- Annelids primarily respire through their skin. They have a simple respiratory system that relies on diffusion across their moist skin.
- **Conclusion:** Annelida does not have gills or pulmonary sacs.

2. **Identify the Respiratory System of Arthropoda:**
- Arthropods have a more complex respiratory system that includes various structures such as tracheae, gills, book gills, and lungs.
- **Conclusion:** Arthropoda does have gills, but it does not have pulmonary sacs.

3. **Identify the Respiratory System of Echinodermata:**
- Echinoderms utilize a water vascular system for respiration, which is quite different from gills or pulmonary sacs.
- **Conclusion:** Echinodermata does not have gills or pulmonary sacs.

4. **Identify the Respiratory System of Mollusca:**
- Mollusca possess specialized respiratory structures known as "ctenidia" (also referred to as comb gills) and some have pulmonary sacs.
- **Conclusion:** Mollusca has both gills (ctenidia) and pulmonary sacs as part of their respiratory system.

5. **Final Conclusion:**
- Based on the analysis, the organism that utilizes gills or pulmonary sacs for respiration is **Mollusca**.

### Answer:
The correct option is **Mollusca**.

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