Which of the following does not occur during breathing? 

Options

A. Brings the air to body temperature
B. Warms up the air
C. Diffusion of gases
D. Cleans up the air

Explanation

To determine which of the following does not occur during breathing, we need to analyze each option provided:

1. **Brings the air to body temperature**: This is a process that occurs during breathing. As air enters the respiratory system, it is warmed to match the body's internal temperature.

2. **Warms up the air**: Similar to the first option, this is also a part of the breathing process. The air is warmed as it passes through the nasal passages and other parts of the respiratory system.

3. **Diffusion of gases**: This does not occur during the act of breathing itself. Instead, diffusion of gases refers to the movement of oxygen and carbon dioxide between the alveoli in the lungs and the blood in the capillaries. This process takes place after breathing, during gas exchange.

4. **Cleans up the air**: The respiratory system has mechanisms, such as mucus and cilia, that help filter and clean the air we breathe. This is indeed a function that occurs during breathing.

Based on this analysis, the option that does not occur during breathing is:

**Answer: Diffusion of gases (Option 3)**