(A) : Natural rubber is a polymer of cis-isoprene
(R) : Poly trans isoprene is called Gutta-percha

Options

A. Both (A) and (R) are true and (R) is the correct explanation of (A)
B. Both (A) and (R) are true (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true

Answer

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

**Assertion (A): Natural rubber is a polymer of cis-isoprene.**
**Reason (R): Poly trans isoprene is called Gutta-percha.**

### Step 1: Analyze the Assertion
- Natural rubber is indeed a polymer made from the monomer isoprene.
- The specific form of isoprene that polymerizes to form natural rubber is the cis form, known as cis-1,4-polyisoprene.
- Therefore, the assertion is **true**.

### Step 2: Analyze the Reason
- Gutta-percha is a polymer of trans-isoprene, which is known as trans-1,4-polyisoprene.
- This means that the reason provided is also **true**.

### Step 3: Determine the Relationship Between Assertion and Reason
- While both the assertion and reason are true, the reason does not explain why natural rubber is a polymer of cis-isoprene. The reason simply states a fact about another polymer (gutta-percha) without linking it to the assertion about natural rubber.

### Conclusion
- Since both the assertion and reason are true, but the reason does not correctly explain the assertion, the correct answer is:
**Option 2: Both assertion and reason are true, but reason is not the correct explanation of assertion.**