The King School has an enrollment of 900 students. The school day at King consists of 6 class peroids, each of which is taught by one teavher, and there is an average of 30 students per class. Of each teacher at King teaches 5 of the 6 peroids and has one peroid free, but no students has a free peroid, how many teachers does the school have?
(A)25
(B)30
(C)36
(D)60
(E)150
Ans:C