A : Higher is the accuracy of measurement, if instrument have smaller least count.
R : Smaller the percentage error, higher is the accuracy of measurement.

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

To solve the assertion and reason question, we need to analyze both statements and their relationship to accuracy in measurement.

### Step-by-Step Solution:

**Step 1: Understand the Assertion**
- The assertion states: "Higher is the accuracy of measurement if the instrument has a smaller least count."
- **Explanation**: Least count is defined as the smallest value that can be measured by an instrument. A smaller least count means that the instrument can measure values more precisely, leading to higher accuracy. Therefore, this assertion is true.

**Step 2: Understand the Reason**
- The reason states: "Smaller the percentage error, higher is the accuracy of measurement."
- **Explanation**: Percentage error is calculated using the formula:
\[ \text{Percentage Error} = \left( \frac{\text{Least Count}}{\text{Original Value}} \right) \times 100 \]
A smaller percentage error indicates that the measurement is closer to the actual value, which corresponds to higher accuracy. Thus, this statement is also true.

**Step 3: Analyze the Relationship Between Assertion and Reason**
- While both the assertion and reason are true, we need to determine if the reason correctly explains the assertion.
- The assertion focuses on the least count directly affecting accuracy, while the reason discusses percentage error, which is indirectly related to least count.
- Therefore, although both statements are true, the reason does not provide a direct explanation for the assertion.

**Conclusion:**
- Both the assertion and reason are true, but the reason does not correctly explain the assertion. Thus, the correct answer is that both statements are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
- Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

---