Emphysema is a condition resulting from

Options

A. cigarette smoking
B. liquor consumption
C. durg addiction
D. reduced oxygen carrying capacity of blood.

Explanation

**Step-by-Step Solution:**

1. **Understanding Emphysema**: Emphysema is a lung disorder characterized by the abnormal distention (inflation) of the air sacs (alveoli) in the lungs, which leads to difficulty in breathing and reduced oxygen exchange.

2. **Identifying Causes**: The question provides four options as potential causes of emphysema:
- A) Cigarette smoking
- B) Liquor consumption
- C) Drug addiction
- D) Reduced oxygen carrying capacity of the blood

3. **Analyzing Each Option**:
- **Option A (Cigarette smoking)**: This is widely recognized as the primary cause of emphysema. Smoking damages the air sacs and the lung tissue, leading to the symptoms of emphysema.
- **Option B (Liquor consumption)**: While excessive alcohol can have various health impacts, it is not directly linked to the development of emphysema.
- **Option C (Drug addiction)**: Similar to liquor consumption, drug addiction can affect overall health but is not a direct cause of emphysema.
- **Option D (Reduced oxygen carrying capacity of the blood)**: This condition can occur due to various reasons (like anemia) but does not directly cause emphysema.

4. **Conclusion**: After analyzing the options, it is clear that the primary cause of emphysema is cigarette smoking. Therefore, the correct answer is **Option A: Cigarette smoking**.

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