The Following MINITAB Output Presents a Confidence Interval for a Population

Multiple Choice

The following MINITAB output presents a confidence interval for a population mean.
$\begin{array}{crrrrc}\hline \text { Variable } & \mathrm{N} & \text { Mean } & \text { StDev } & \text { SE Mean } & 99 \% \mathrm{CI} \\\mathrm{x} & 72 & 84.4238 & 33.8186 & 3.9856 & (73.874,94.973) \\\hline\end{array}$
How many degrees of freedom are there?

A) 3.9856
B) 72
C) 73
D) 71