Mark the true statement among the following with reference to normal breathing.

Options

A. inspiration is a passive process whereas expiration is active
B. inspiration is a active process whereas expiration is passive
C. inspiration and expiration are active processes
D. inspiration and expiration are passive processes

Explanation

To determine the true statement regarding normal breathing, let's analyze the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding Normal Breathing**:
- Normal breathing involves two main processes: inhalation (inspiration) and exhalation (expiration).
- Inspiration is the intake of oxygen, while expiration is the release of carbon dioxide.

2. **Evaluating the Statements**:
- **Statement 1**: "Inspiration is a passive process whereas expiration is active."
- This statement is incorrect. Inspiration is an active process because it requires energy for the contraction of the diaphragm and intercostal muscles.

- **Statement 2**: "Inspiration is an active process whereas expiration is passive."
- This statement is correct. Inspiration involves muscle contraction and energy expenditure, while expiration can occur passively when the muscles relax.

- **Statement 3**: "Inspiration and expiration are active processes."
- This statement is incorrect. While inspiration is active, expiration is generally passive.

- **Statement 4**: "Inspiration and expiration are passive processes."
- This statement is incorrect. As mentioned, inspiration is an active process.

3. **Conclusion**:
- The only true statement among the options is **Statement 2**: "Inspiration is an active process whereas expiration is passive."

### Final Answer:
The true statement regarding normal breathing is: **Inspiration is an active process whereas expiration is passive.**

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