In breathing movements, air volume can be estimated by

Options

A. Stethoscope
B. Hygrometer
C. Sphygmomanometer
D. Spirometer

Answer

To solve the question regarding which instrument is used to estimate air volume in breathing movements, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which instrument can be used to estimate the volume of air during breathing movements.

2. **Evaluate the Options**:
- **Option 1: Stethoscope**: This instrument is primarily used to listen to heartbeats and lung sounds, not to measure air volume.
- **Option 2: Hygrometer**: This device measures humidity levels in the air, not related to breathing air volume.
- **Option 3: Sphygmomanometer**: This instrument is used to measure blood pressure, which is unrelated to air volume in the lungs.
- **Option 4: Spirometer**: This is the correct instrument used to measure the volume of air inhaled and exhaled during breathing.

3. **Identify the Correct Answer**: Based on the evaluation, the correct answer is **Option 4: Spirometer**.

### Final Answer:
The instrument used to estimate air volume in breathing movements is the **Spirometer**.

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