Which shows solutions to x + 3y = 7 if x and y must be whole numbers. A. {(0, 5), (1, 3), (2, 1)} B. {(2, 1), (1, 4), (0, 7)} C. {(1, 2), (4, 1), (7, 0)} D. {(0, 5), (1, 4), (2, 1)}