A. 1 → C, 2 → A, 3 → B, 4 → D
B. 1 → A, 2 → F, 3 → C, 4 → E
C. 1 → B, 2 → D, 3 → E, 4 → A
D. 1 → D, 2 → B, 3 → C, 4 → F