The five items: A, B, C, D, and E are pushed in a stack, one after the other starting from A. The stack is popped four times and each element is inserted in a queue. Then two elements are deleted from the queue and pushed back on the stack. Now one item is popped from the stack. The popped item is
- A. A
- B. B
- C. C
- D. D
Answer: D. D
Explanation: Stack: [A,B,C,D,E]. Pop 4: E, D, C, B. Queue: E, D, C, B. Delete 2 from Q: E, D. Push to Stack: [A, E, D]. Pop 1: D.