Assertion. SNS slows down peristalsis.
Reason. Parasympathetic nervous system does the same.

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 analyze the assertion and reason provided in the question, we will break it down step by step.

### Step 1: Understand the Assertion
- **Assertion**: "SNS slows down peristalsis."
- The Sympathetic Nervous System (SNS) is responsible for the body's 'fight or flight' responses. When activated, it generally inhibits non-essential functions, including digestion. This means that SNS does indeed slow down peristalsis, which is the involuntary contraction of muscles in the digestive tract that moves food along.

### Step 2: Understand the Reason
- **Reason**: "Parasympathetic nervous system does the same."
- The Parasympathetic Nervous System (PNS), on the other hand, is responsible for 'rest and digest' functions. It promotes digestion and increases peristalsis. Therefore, the statement that the PNS slows down peristalsis is incorrect.

### Step 3: Evaluate the Truth of Assertion and Reason
- The assertion is true: SNS does slow down peristalsis.
- The reason is false: PNS does not slow down peristalsis; it actually enhances it.

### Step 4: Conclusion
- Since the assertion is true and the reason is false, the correct answer is that the assertion is true but the reason is false.

### Final Answer
- The correct option is: A is true, but R is false.