Fill in the following blanks with suitable words:
In insects, exchange of gases occurs through …………

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks to fill in the blank regarding how insects exchange gases.

2. **Identifying the Process**: Insects, like all organisms, need to exchange gases to survive. The primary gases involved in this process are oxygen (which is taken in) and carbon dioxide (which is expelled).

3. **Recognizing the Organs Involved**: Different organisms have different structures for gas exchange. For example:
- Fish use gills.
- Humans use lungs.
- Earthworms use their moist skin.

4. **Focusing on Insects**: Insects have a unique system for gas exchange. They do not have lungs or gills. Instead, they have a specialized network of tubes.

5. **Naming the System**: This network of tubes in insects is known as the **tracheal system**.

6. **Identifying the Openings**: The small openings on the sides of an insect's body through which air enters are called **spiracles**.

7. **Filling in the Blank**: Based on the above information, the correct word to fill in the blank is **tracheal system**.

**Final Answer**: In insects, exchange of gases occurs through **tracheal system**.

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