概率题 ！求解！！Math1 25

鸡腿

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

A.  5
B.  6
C.  9
D.  24
E.   36
求解。。概率是我的死穴啊。。特别是这道题啊。。。有没有大神告诉我怎么做啊~！！！

鸡腿

恩。。谢谢啦。。看来不需要用到概率只是拉。。