The Following Information Was Obtained from Independent Random Samples Taken

Multiple Choice

The following information was obtained from independent random samples taken of two populations. Assume normally distributed populations with equal variances. $$\begin{array} { l l l } & \text { Sample 1 } & \text { Sample 2 } \\\text { Sample Mean } & 45 & 42 \\\text { Sample Variance } & 85 & 90 \\\text { Sample Size } & 10 & 12\end{array}$$
The standard error of $\bar { x } _ { 1 }$ - $\bar { x } _ { 2 }$ is

A) 3.0.
B) 4.
C) 8.372.
D) 19.48.