A certain class, consisting of a lecture and a question-and-answer session, lasted from 2:45 to 4:30 one afternoon. If the lecture lasted from 2:45 to 4:15, then the question-and-answer session was what fraction of the total class time?
-
A 1/7
-
B1/6
-
C 1/5
-
D 1/4
-
E1/3