Which relation defined by a set of ordered pairs is a function?


A {(2, 6), (3, 6), (4, 5), (6, 6), (6, 7)}


B {(6, 2), (6, 3), (5, 4), (6, 6), (7, 6)}


C {(2, 6), (3, 6), (4, 5), (6, 6), (7, 6)}


D {(–2, 6), (3, –6), (–4, 5), (6, –6), (6, –7)}