64. What is the output of the following code？

(A) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
(B) 5 2 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
(C) 5 10 15 20
(D) 16 21