Q25:
A photographer will arrange 6 people of 6 different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row.  The heights of the people within each row must increase from left to right, and each person in the second row must be taller than the person standing in front of him or her.  How many such arrangements of the 6 people are possible?

A.        5
B.        6
C.        9
D.        24
E.        36
请问怎么解答，漫无头绪

456
123

356
124

346
125

256
134

246
135

所以一共5个，我觉得是A。你按这个顺序排以下就好了，赫赫。

好的谢谢！
考试的时候要完成这个过程不容易啊