单选题：Given the popping sequence of a stack as { a, b, c, d, e, f }. A

Given the popping sequence of a stack as { a, b, c, d, e, f }. Among the following, the impossible pushing sequence is: @[B](2)

A. c b a f e d
B. d f e a c b
C. f e a b c d
D. f e d a b c




A.c b a f e d
B.d f e a c b
C.f e a b c d
D.f e d a b c


答案：B