Assertion. Acetylcholine transmits the nerve impulse across a synpase .
Reason. Acetylcholine is secreted by adrenergic neurons.

Options

A. If both A and R are true and R is the correct explanation of A.
B. If both A and R are true and R is not the correct explanation of A.
C. If A is true but R is false.
D. If both A and R are false.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Acetylcholine transmits the nerve impulse across a synapse."
- This is true because acetylcholine is a well-known neurotransmitter that plays a crucial role in transmitting signals between neurons at the synapse. When a nerve impulse reaches the end of a neuron, acetylcholine is released into the synaptic cleft and binds to receptors on the next neuron, facilitating the transmission of the nerve impulse.

2. **Understanding the Reason**:
- The reason states that "Acetylcholine is secreted by adrenergic neurons."
- This statement is false. Acetylcholine is primarily secreted by cholinergic neurons, not adrenergic neurons. Adrenergic neurons release norepinephrine (noradrenaline) as their neurotransmitter. Therefore, the reason does not correctly explain the assertion.

3. **Conclusion**:
- Since the assertion is true and the reason is false, we conclude that the assertion stands alone without the support of the reason.
- The correct answer is that the assertion is true, but the reason is false.

### Final Answer:
- The assertion is true, but the reason is false.