Two Independent Samples of Sizes 50 and 50 Are Randomly $\mu _ { 1 } - \mu _ { 2 }$

Two independent samples of sizes 50 and 50 are randomly selected from two populations to test the difference between the population means, $\mu _ { 1 } - \mu _ { 2 }$ . The sampling distribution of the sample mean difference $\bar { x } _ { 1 } - \bar { x } _ { 2 }$ is: $\begin{array}{|l|l|}\hline A&\text { normally distributed.}\\\hline B&\text { approximately normal.}\\\hline C&\text { \( t \)-distributed with 98 degrees of freedom.}\\\hline D&\text { chi-squared distributed with 99 degrees of freedom.}\\\hline\end{array}$