Answer is (D)
A: Increments the Count by 1 at each index that is equal to the ASCII value of the alphabet it is pointing at
B: Decrements the count by 1 at each index that is equal to the ASCII value of the alphabet it is pointing at . Also it increments the loop counter for next iteration.
If one string is permutation of other ,there would have been equal increments and decrements at each index of array and So count should contain zero at each index.that is what the loop checks at last and if any non-zero elements is found, it returns 0 indicating that strings are not anagram to each other.