In F-test, S₁² and S₂² are defined as

A. $${S_1}^2 = \frac{{\sum {{\left( {{X_1} - {{\overline X }_1}} \right)}^2}}}{{{n_1} - 1}},\,{S_2}^2 = \frac{{\sum {{\left( {{X_2} - {{\overline X }_1}} \right)}^2}}}{{{n_1} - 1}}$$

B. $${S_1}^2 = \frac{{\sum {{\left( {{X_1} - {{\overline X }_1}} \right)}^2}}}{{{n_1} - 1}},\,{S_2}^2 = \frac{{{{\left( {{X_2} - {{\overline X }_2}} \right)}^2}}}{{{n_1} - 1}}$$

C. $${S_1}^2 = \frac{{\sum {{\left( {{{\overline X }_1} - {X_1}} \right)}^2}}}{{{n_1} - 1}},\,{S_2}^2 = \frac{{\sum {{\left( {{{\overline X }_2} - {X_2}} \right)}^2}}}{{{n_2} - 1}}$$

D. None of the above

Answer: Option B