Based on the Following Results, Which Would Be the Correct

Based on the following results, which would be the correct use of the formula t = (M1-M2) /S_Difference? Sample 1: Mean = 60; Variance of the distribution of means = 2.
Sample 2: Mean = 50; Variance of the distribution of means = 7.

A) t = (7-2) / 50 + 60
B) t = (60-50) / 4 + 49
C) t = 60-50 / 3
D) t = 60-50 / 9