2 men and 2 women are lined up in a row. What is the number of cases where they stand with each other in turn? (The number of cases in which men (or women) do not stand next to each other)	Choose the most appropriate option:	A) 4	B) 15	C) 18	D) 21	E) 24

Rationale: the list should be wmwmw . hence , from women 2 ! and men 2 ! , we get ( 2 ! ) ( 2 ! ) = 4 . therefore , the correct answer is a .
Answer: A