Thirty randomly selected students took the calculus final. If the sample mean was 89 and the standard deviation was 6.2, construct a 99% confidence interval of the mean score of all students. Assume that the population has a normal distribution.
A. 85.89<µ<92.11
B. 85.88<µ<92.12
C. 87.08<µ<90.92
D. 86.21<µ<91.79