Which confidence interval is the narrowest?

A) 99.9%
B) 99%
C) 95%
D) 90%

A narrower confidence interval means that we are more certain about the population parameter estimate. As we increase the confidence level, the width of the interval increases, and the likelihood of capturing the true population parameter also increases. Therefore, a 90% confidence interval will be narrower than a 95%, 99%, or 99.9% confidence interval.