单选题：Consider a special queue which is a linear structure that allows

Consider a special queue which is a linear structure that allows insertions at one end, yet deletions at both ends. Given an insertion sequence { 21, 15, 36, 63, 42 }. Which of the following is NOT a possible deletion sequence?




A.21 36 15 42 63
B.42 21 36 15 63
C.15 36 21 63 42
D.36 42 21 63 15


答案：B