某事故树的最小割集为：Kl＝{X1}，K2＝{X2，X3}，K3＝{X2，X4，X5}，则结构重要程度为()。
A.I(4)＞I(2)＞I(3)＞I(1)＝I(5)
B.I(1)＞I(2)＞I(3)＞I(4)＝I(5)
C.I(1)＞I(5)＞I(3)＞I(4)＝I(2)
D.I(5)＞I(3)＞I(2)＞I(1)＝I(4)