One function of parasympathetic nervous system is

Options

A. contraction of hair muscles
B. stimulation of sweat glands
C. acceleration of heartbeat
D. constriction of pupil

Explanation

To answer the question about one function of the parasympathetic nervous system, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of the Parasympathetic Nervous System**: The parasympathetic nervous system is part of the autonomic nervous system, which is responsible for regulating involuntary bodily functions. Its primary role is to conserve energy and promote a state of rest and relaxation.

2. **Identify Key Functions**: Some of the key functions of the parasympathetic nervous system include:
- Slowing down the heart rate
- Stimulating digestion
- Constricting the pupils (the openings in the center of the eyes)

3. **Analyze the Options Given**: The options provided in the question are:
- Contraction of hair muscles
- Stimulation of sweat glands
- Acceleration of heartbeat
- Contraction of pupils

4. **Evaluate Each Option**:
- **Contraction of hair muscles**: This is not a primary function of the parasympathetic nervous system.
- **Stimulation of sweat glands**: This is primarily controlled by the sympathetic nervous system, especially during stress or heat.
- **Acceleration of heartbeat**: This is also a function of the sympathetic nervous system, not the parasympathetic.
- **Contraction of pupils**: This is a function of the parasympathetic nervous system, as it helps control the amount of light entering the eye and is associated with relaxation.

5. **Select the Correct Answer**: Based on the analysis, the correct function of the parasympathetic nervous system from the options provided is the **contraction of pupils**.

### Final Answer:
One function of the parasympathetic nervous system is the **contraction of pupils**.

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