单选题：Given the shape of a binary tree shown by the figure below. If

Given the shape of a binary tree shown by the figure below. If its postorder traversal sequence is { `e`, `a`, `c`, `b`, `d`, `f` }, then the node on the same level of `c` must be: @[C](3)




A. `e`
B. `f`
C. `a`
D. None




A.`e`
B.`f`
C.`a`
D.None


答案：C