The main function of acetylcholine is to :

Options

A. Increase heart beat
B. Help in synaptic transmission of nerve impulse
C. Help in conduction of nerve impulse through axon
D. Control reflex action

Answer

To determine the main function of acetylcholine, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Acetylcholine**: Acetylcholine is a neurotransmitter, which means it is a chemical messenger that transmits signals in the nervous system.

2. **Identifying the Functions**: Acetylcholine plays several roles in the body, particularly in the nervous system and muscular system. It is involved in:
- Synaptic transmission between neurons.
- Stimulating muscle contraction at the neuromuscular junction.
- Modulating heart rate through its action on the parasympathetic nervous system.

3. **Analyzing the Options**:
- **Increase the heart rate**: While acetylcholine does have a role in heart function, it primarily decreases heart rate through the parasympathetic nervous system.
- **Help in the synaptic transmission of nerve impulses**: This is a primary function of acetylcholine, as it facilitates communication between neurons.
- **Help in the conduction of nerve impulses through the axon**: This is not a direct function of acetylcholine; conduction occurs along the axon itself, primarily through electrical signals (action potentials).
- **Control reflex action**: While acetylcholine may play a role in reflex arcs, it is not the primary function attributed to it.

4. **Selecting the Correct Answer**: Given the analysis, the most accurate description of acetylcholine's main function is that it helps in the synaptic transmission of nerve impulses.

### Final Answer:
The main function of acetylcholine is to help in the synaptic transmission of nerve impulses.

---