Find the Sample Size

Find the sample size.
-Top management at a large software company wishes to estimate the average number
Of hours its firm's professional employees volunteer in the local community. Based on
Past similar studies, the standard deviation was found to be 2.22 hours. If top
Management wants to estimate the average number of hours volunteered per month by
Their professional staff to within one hour with 99% confidence, how many randomly
Selected professional employees would they need to sample?

A) 19
B) 25
C) 54
D) 44
E) 33