which of the following conditions is responsible for increase in ventilation rate of lungs ?

Options

A. (a) increase in `O_(2)` content of inhaled air
B. (b) decrease in `O_(2)` content of exhaled air
C. (c) increase of `CO_(2)` content in inhaled air
D. (d) increase of `CO_(2)` content in exhaled air

Answer

To determine which condition is responsible for an increase in the ventilation rate of the lungs, we need to understand the factors that influence breathing.

### Step-by-Step Solution:

1. **Define Ventilation Rate**:
- Ventilation rate refers to the amount of air inhaled or the number of breaths taken per minute. It is crucial for maintaining proper gas exchange in the lungs.

2. **Understand the Role of Oxygen and Carbon Dioxide**:
- During respiration, oxygen is inhaled and carbon dioxide is exhaled. The balance of these gases is vital for healthy breathing.

3. **Identify Triggers for Increased Ventilation**:
- An increase in ventilation rate, also known as hyperventilation, typically occurs when there is a need to expel excess carbon dioxide (CO2) from the body. This can happen when CO2 levels in the blood rise, leading to a drop in blood pH (increased acidity).

4. **Analyze the Options**:
- **Option A**: Increase in oxygen content in inhaled air - This does not trigger hyperventilation; rather, it is a condition that would not require increased breathing.
- **Option B**: Decrease in oxygen content in exhaled air - This option is irrelevant to the inhalation process and does not directly cause an increase in ventilation.
- **Option C**: Increase of CO2 content in inhaled air - This condition would indeed trigger hyperventilation as the body attempts to expel the excess CO2 and restore balance.
- **Option D**: Decrease in carbon dioxide content in exhaled air - Similar to option B, this does not relate to the inhalation process and does not cause increased ventilation.

5. **Conclusion**:
- The correct answer is **Option C**: Increase of CO2 content in inhaled air, which leads to an increase in ventilation rate to expel the excess CO2.