Which relation describes a function?

a) {(0, 0), (0, 2), (2, 0), (2, 2)}
b) {(−2, −3), (−3, −2), (2, 3), (3, 2)}
c) {(2, −1), (2, 1), (3, −1), (3, 1)}
d) {(2, 2), (2, 3), (3, 2), (3, 3)}

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Will mark determine whether the conjecture is true or false. give a counterexample for any false conjecture. given: points r, s, and t conjecture: r, s, and t are coplanar. a) false; the points do not have to be in a straight line. b) true c) false; the points to not have to form right angles. d) false; one point may not be between the other two.

Ithink i know it but i want to be sure so can you me out ?