When a researcher moves from a 95% confidence level to a 99% confidence level, the confidence interval for the mean becomes ______.

A) wider
B) normally distributed
C) statistically significant
D) narrower

When a researcher moves from a 95% confidence level to a 99% confidence level, they are increasing the level of certainty that the population mean falls within the confidence interval. As a result, the confidence interval will become wider, because the researcher needs to account for a greater range of possible values within the interval to maintain the same level of confidence.