In breathing movements, air volume can be estimated by:

Options

A. stethoscope
B. sphygmomanometer
C. auxanometer
D. spirometer

Explanation

To estimate the air volume during breathing movements, we can follow these steps:

1. **Understand the Purpose of Breathing**: Breathing, or pulmonary ventilation, is essential for facilitating gaseous exchange in the lungs, allowing oxygen to enter the body and carbon dioxide to be expelled.

2. **Identify the Need for Measurement**: To assess how much air is being inhaled or exhaled during breathing, we need a method to measure this air volume accurately.

3. **Introduce the Spirometer**: The device specifically designed for measuring the volume of air exchanged during breathing is called a spirometer. It allows individuals to inhale and exhale into a mouthpiece.

4. **Function of the Spirometer**: When a person breathes into the spirometer, it records the volume of air inhaled during inspiration and the volume expelled during expiration. This data helps in understanding lung function and respiratory health.

5. **Eliminate Incorrect Options**: Other devices mentioned, such as a stethoscope (for heart sounds), sphygmomanometer (for blood pressure), and oxenometer (not related to human physiology), do not measure air volume in breathing movements.

6. **Conclusion**: Therefore, the correct answer to the question regarding the estimation of air volume during breathing movements is the spirometer.

**Final Answer**: The air volume in breathing movements can be estimated by a spirometer.

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