Answer: Increasing the number of replications

**Explanation:** In Monte Carlo simulation, the standard error of the estimated mean decreases as the square root of the number of replications (sample size). This is based on the Central Limit Theorem: - **Standard Error = σ/√n**, where σ is the standard deviation and n is the number of replications Therefore: - **Option A**: Increasing variance would actually increase the standard error - **Option B**: Confidence level affects the width of confidence intervals but doesn't reduce standard error - **Option C**: Changing the expected value doesn't affect the precision of the estimate - **Option D**: Increasing the number of replications reduces the standard error proportionally to 1/√n This is a fundamental property of Monte Carlo methods - more simulations lead to more precise estimates.

Author: LeetQuiz Editorial Team