airene

1. Which of the following is NOT a function? Select one.

(a) {(4,7)(7,4)(-4,-7)(-7,-4)}

(b) {(5,2)(6,2)(7,2)(8,2)}

(c) {(0,2)(-1,6)(3,-9)(12,-4)}

(d) {(2,4)(8,1)(-3,-4)(2,7)}