George D Took Four Exams in American History $\mu$ 'S And $\sigma$

George D. took four exams in American history. On each he made a score of 89. The $\mu$ 's and $\sigma$ 's for these four tests are given below. On which test did George's 89 represent his best performance?

A) $\mu$ =95, $\sigma$ =6
B) $\mu$ =95, $\sigma$ = 12
C) $\mu$ =92, $\sigma$ =2
D) $\mu$ =91, $\sigma$ = 1.