Give a quick stream of consciousness before answering the following question. There are 6 fictions and 6 non-fictions. How many cases are there such that 2 fictions and 2 non-fictions are selected from them?
Options:
(A) 90
(B) 120
(C) 225
(D) 180
(E) 200
Number of ways of selecting 2 fiction books = 6C2
Number of ways of selecting 2 non fiction books = 6C2
6C2 * 6C2 = 15 * 15 = 225
The answer: (C).