Which set of ordered pairs (x, y) could represent a linear function?
A = {(-2,5), (0, 3), (2, 1), (5,-2)}
B = {(2,9), (4, 5), (5,2), (6,0)}
C = {(-3,-8), (0, -4), (3,-1), (6,2)}
D = {(-2,3), (0, -1), (2,-4), (4,-7)}