Exoskeleton is the skeleton which is present

Options

A. outside the body of an organism
B. inside the body of an organism
C. only in insects
D. none of these.

Explanation

### Step-by-Step Solution:

1. **Understanding Exoskeleton**:
- The term "exoskeleton" refers to a type of skeleton that is located on the outside of an organism's body. The prefix "exo-" means "outside."

2. **Function of Exoskeleton**:
- The primary function of an exoskeleton is to protect the body of the organism from external harm, providing a hard outer structure.

3. **Examples of Exoskeletons**:
- Exoskeletons can be found in various organisms. For instance:
- **Cockroach**: The exoskeleton is made of chitin, which is a tough, protective material.
- **Snail**: The exoskeleton is made of calcareous substances, primarily calcium phosphate, which forms a hard shell.

4. **Comparison with Human Skeleton**:
- In humans, the skeleton is internal and made of bones, which is different from an exoskeleton. However, the human skeleton also serves a protective function.

5. **Identifying the Correct Option**:
- Based on the definition and examples provided, the correct statement regarding exoskeletons is that they are located outside the body of the organism.

6. **Conclusion**:
- Therefore, the correct answer to the question is that the exoskeleton is the skeleton which is present outside the body of the organism.