The function letters in the following program creates a dynamically allocated string with a given number of letters of the alphabet starting with A. Match the correct code to the missing spots. A correct implementation would result in the shown main function printing the 26-letters of the alphabet in order, i.e. ABCDEFGHIJKLMNOPQRSTUvwxYZ char* letters(int num if Cnum 0) return NULL; AAA result malloc(BBB); CCC ch 'A; for (int i-0; i