Chitin occurs in

Options

A. Crab
B. prawn
C. Agaricus
D. All the above.

Answer

**Step-by-Step Solution:**

1. **Understanding Chitin:**
- Chitin is a complex polysaccharide that serves as a structural component in various organisms. It is primarily found in the exoskeletons of arthropods and the cell walls of fungi.

2. **Analyzing the Options:**
- **Option 1: Crab**
- Crabs are crustaceans, which are part of the arthropod family. They have an exoskeleton made of chitin.
- **Option 2: Prawn**
- Prawns are also crustaceans and belong to the same group as crabs. They too have an exoskeleton composed of chitin.
- **Option 3: Agaricus**
- Agaricus refers to a genus of mushrooms, which are fungi. The cell walls of fungi are made of chitin, making this option valid as well.
- **Option 4: All of the above**
- Since chitin is present in crabs (exoskeleton), prawns (exoskeleton), and Agaricus (cell wall), this option encompasses all the previous options.

3. **Conclusion:**
- Since chitin is found in crabs, prawns, and Agaricus, the correct answer is **Option 4: All of the above**.