单选题
编号：2690455
1. What is the most appropriate test statistic for constructing confidence intervals for the population mean when the population is normally distributed, but the variance is unknown?
- A.The z-statistic at
with n degrees of freedom. - B.The t-statistic at /2 with n degrees of freedom.
- C.The t-statistic at /2 with n-1 degrees of freedom.