Q13) By using a stack and pop push operation and the input string: (A, B, C, D, E, F) sequentially from left to right, which output can possible? A) BEC B) BDF C) EDCBA D EDCAB E DBF ********* ***** ******* Q14) If the prefix of an expression is equal to: ++ABD/E+FAD, what is its postfix expression? A)AB+DE+FAD/+ B)AB+DEFAD+/+ C)AB+DE-F/A+D* D)AB+DEFAD+/+ E)AB+DE+FAD*+/ *** *** Q15) The time complexity of the following C function is (assume n > 0) int recursive (int n) { if (n == 1) return (1); else return (recursive (n - 1) + recursive (n - 1)); } A) (2nlogn) B) O(n) C) O(n log n) D) O(n2) E) 0(2n)