Please answer the following question by reasoning step-by-step.
The average of five results is 48 and that of the first four is 45. The fifth result is?\nOptions:\n(A) 50\n(B) 60\n(C) 70\n(D) 80\n(E) 90

(B)
5 * 48 – 4 * 45 = 60.

Thus, the answer is (B)