A : Postganglionic nerve fibre of parasympathetic nervous system have acetylcholine while sympathetic nervous system have adrenaline as the neurotransmitter.
R : Sympathetic nervous system inhibit the intestinal peristalsis while parasympathetic stimulate peristalsis.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4).

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion (A):**
- The assertion states that postganglionic nerve fibers of the parasympathetic nervous system release acetylcholine, while those of the sympathetic nervous system release adrenaline (epinephrine).
- This is true as the parasympathetic nervous system primarily uses acetylcholine as its neurotransmitter for postganglionic fibers, whereas the sympathetic nervous system uses norepinephrine (or adrenaline) for most postganglionic fibers.

2. **Understanding the Reason (R):**
- The reason states that the sympathetic nervous system inhibits intestinal peristalsis, while the parasympathetic nervous system stimulates it.
- This is also true. The sympathetic nervous system is responsible for the "fight or flight" response, which diverts energy away from digestion (hence inhibiting peristalsis). In contrast, the parasympathetic nervous system promotes "rest and digest" activities, stimulating peristalsis.

3. **Evaluating the Relationship Between A and R:**
- Both the assertion and reason are correct.
- Furthermore, the reason provides a correct explanation for the assertion. The release of adrenaline by the sympathetic nervous system leads to the inhibition of peristalsis, while the release of acetylcholine by the parasympathetic nervous system promotes it.

4. **Conclusion:**
- Since both the assertion and reason are true, and the reason correctly explains the assertion, the correct answer is that both A and R are true, and R is the correct explanation of A.

**Final Answer:**
Both assertion (A) and reason (R) are true, and R is the correct explanation of A.

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