The best method to reduce random error is

Options

A. a. To change the instrument used for measurement
B. b. To take help of experienced observer
C. c. To repeat the experiment many times and to take the average results
D. d. None of the above

Explanation

To solve the question regarding the best method to reduce random error, we will analyze the options provided and determine the most effective approach.

### Step-by-Step Solution:

1. **Understanding Random Error**:
- Random errors are unpredictable variations in measurements that can occur due to various factors such as environmental changes, instrument limitations, or human errors.

2. **Evaluating the Options**:
- **Option A**: Change the instrument used for measurement.
- While using a different instrument may help in some cases, it does not necessarily reduce random errors inherent in the measurement process itself.

- **Option B**: Take the help of an experienced observer.
- An experienced observer may reduce systematic errors or improve measurement accuracy, but it does not directly address random errors.

- **Option C**: Repeat the experiment many times and take the average result.
- This method is effective because averaging multiple measurements can help to minimize the impact of random errors. By taking several observations, the random fluctuations tend to cancel each other out, leading to a more reliable average result.

- **Option D**: None of these.
- This option suggests that none of the above methods are effective, which is incorrect based on our analysis.

3. **Conclusion**:
- After evaluating all the options, we find that **Option C** is the best method to reduce random error. By repeating the experiment multiple times and calculating the average, we can effectively minimize the impact of random variations in our measurements.

### Final Answer:
The best method to reduce random error is **C: Repeat the experiment many times and take the average result**.

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