(A) If Amanda does not buy green in-line skates, then Tom does not buy a red skateboard.
(B) If Tom does not buy a red skateboard, then Amanda does not buy green in-line skates.
(C) If Amanda buys green in-line skates, then Tom buys a red skateboard.
(D) If Tom buys a red skateboard, then Amanda does not buy green in-line skates.