Read the following SAT test question and then click on a button to select your answer.

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) 1/4
(B) 1/3
(C) 5/12
(D) 7/12
(E) 1/2

来源:可可英语 http://www.kekenet.com/sat/201507/385875.shtml