Which of the following respires by gills?

Options

A. Prawn
B. Crocodile
C. Whale
D. Frog.

Answer

To determine which of the following organisms respires by gills, we will analyze each option provided: prawn, crocodile, whale, and frog.

### Step-by-Step Solution:

1. **Identify the Organisms**:
- The options given are prawn, crocodile, whale, and frog.

2. **Analyze Each Option**:
- **Prawn**:
- Prawns are aquatic arthropods. They possess gills, which are specialized organs for respiration in water. Gills allow for the exchange of gases (oxygen and carbon dioxide) in the aquatic environment.
- **Crocodile**:
- Crocodiles are reptiles. They primarily respire through lungs, similar to other reptiles and mammals. Therefore, they do not use gills for respiration.
- **Whale**:
- Whales are mammals that live in the water. They also breathe using lungs, not gills. This means they cannot respire through gills.
- **Frog**:
- Frogs are amphibians. While they can respire through their skin (cutaneous respiration) when in water, they primarily use lungs for breathing as adults. Thus, they do not respire by gills.

3. **Conclusion**:
- Based on the analysis, the only organism from the options that respires by gills is the **prawn**.

### Final Answer:
The correct answer is **A) Prawn**.