int mystery(int list[], int first, int last){  if (first == last)     return list[first];  else     return list[first] + mystery(list, first + 1, last);}
Consider the accompanying definition of the recursive function mystery. Given the declaration:int beta[10] = {2, 5, 8, 9, 13, 15, 18, 20, 23, 25};What is the output of the following statement?cout << mystery(beta, 4, 7) << endl;

A. 27
B. 33
C. 55
D. 66

Answer: D