In insects, respiratory gas exchange occurs through

Options

A. gills
B. tracheae
C. skin
D. lungs

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the mechanism of respiratory gas exchange in insects. We need to identify the correct structure or system responsible for this process.

2. **Identifying the Options**: The options mentioned in the transcript include gills, trachea, skin, and lungs. We need to evaluate each of these in relation to insects.

3. **Evaluating Gills**: Gills are primarily found in aquatic animals such as fish. They are not present in insects, so this option can be eliminated.

4. **Evaluating Skin**: Skin respiration is common in certain organisms, particularly in annelids (like earthworms). Insects do not rely on skin for gas exchange, so this option is also incorrect.

5. **Evaluating Lungs**: Lungs are found in mammals, including humans, and are not a feature of insects. Therefore, this option is incorrect as well.

6. **Identifying the Correct Answer**: The correct mechanism for gas exchange in insects is through the tracheal system. This system consists of a network of tubes (tracheae) that transport air directly to the tissues. The tracheae open to the outside through small openings called spiracles.

7. **Conclusion**: Based on the evaluation of the options, the correct answer is that respiratory gas exchange in insects occurs through the trachea.

**Final Answer**: In insects, respiratory gas exchange occurs through the trachea.

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