15. Consider the following C code. Please indicate the value of x after execution.(A) 8 (B) 11 (C) 14 (D) 17 (E) 20

13. Given a binary tree as follows, please indicate the result of pre-order traversal.(A) 7, 5, 28, 40, 36, 12, 79, 50, 49, 86, 96, 81, 99, 43(B) 5, 7, 12, 28, 36, 40, 43, 49, 50, 79, 81, 86, 96, 99(C) 43, 12, 5, 36, 7, 28, 40, 99, 81, 49, 96, 50, 86, 79(D) 43, 12, 99, 5, 36, 81, 7, 28, 40, 49, 96, 50, 86, 79(E) 43, 12, 5, 7, 36, 28, 40, 99, 81, 49, 50, 79, 96, 86