In the nostril the air is :

Options

A. warmed
B. filtered
C. moistened
D. all of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the conditions of air in the nostrils. We need to identify what happens to the air as it passes through the nostrils before reaching the lungs.

2. **Identify the Functions of the Nostrils**: The nostrils are the entry points of air into the respiratory system. They play a key role in preparing the air for the lungs.

3. **Warming the Air**: As air enters through the nostrils, it is warmed. The body temperature is higher than that of the outside air, so the air is brought up to body temperature to ensure it is suitable for gas exchange in the lungs.

4. **Filtering the Air**: The nostrils also filter the air. They trap dust, pollen, and other foreign particles using the mucous membranes and tiny hairs (cilia) present in the nasal passages. This prevents harmful substances from entering the lungs.

5. **Moistening the Air**: Additionally, the air is moistened. The mucous membranes in the nostrils add moisture to the air, preventing the alveoli from drying out. This is crucial for maintaining the moisture necessary for effective gas exchange.

6. **Conclusion**: Since the air is warmed, filtered, and moistened in the nostrils, the correct answer to the question is that in the nostrils, the air undergoes all of these processes.

7. **Final Answer**: Therefore, the answer is **D. All of these**.

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