A 6-sided number cube, with faces numbered 1 through 6, is to be rolled twice. What is the probability that the number that comes up on the first roll will be less than the number that comes up on the second roll?
(A) 1 over 4
(B) 1 over 3
(C) 5 over 12
(D) 7 over 12
(E) 1 over 2