Which of the following relations describes a function?
OA. {(-3,-4), (-4,-3), (3, 4), (4,3)}
OB. {(3,-1), (3, 1), (4, -1), (4, 1) }
OC. {(3, 3), (3, 4), (4,3), (4,4)}
OD. {(0,0), (0, 3), (3, 0), (3, 3) }
