The apparatus for measuring the rate of breathing is

Options

A. Potometer
B. Oxgenometer
C. Autometer
D. Respirometer

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the apparatus used to measure the rate of breathing. This involves identifying the correct device from a list of options.

2. **Evaluating the Options**:
- **Photometer**: This device measures the rate of water uptake, not breathing rate.
- **Oxygenometer**: This device measures the oxygen levels in the body, but it does not directly measure the rate of breathing.
- **Automometer**: This device is related to batteries and does not pertain to measuring breathing.
- **Respirometer**: This is the device specifically designed to measure the rate of breathing.

3. **Identifying the Correct Answer**: After evaluating all the options, the respirometer is the only device that accurately measures the rate of breathing.

4. **Conclusion**: Therefore, the correct answer to the question is the **respirometer**.

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