While Testing for Equality of Variances, Which of the Following $\sigma \frac{2}{1}-\sigma \frac{2}{2}$

Multiple Choice

While testing for equality of variances, which of the following formulae gives the F-test statistic?

A)
$\sigma \frac{2}{1}-\sigma \frac{2}{2}$

B)
$\frac{\bar{x}-\mu_{0}}{\sigma / \sqrt{n}}$

C)
$\frac{\bar{x}-\mu_{0}}{\mathrm{~s} / \sqrt{n}}$

D)