Which set of ordered pairs represents a function?

Question

A {(22, 5), (23, 10), (22, 7), (23, 5)}
B {(22, 5), (26, 10), (23, 7), (23, 5)}
C {(22, 10), (23, 10), (24, 7), (25, 5)}
D {(24, 10), (23, 6), (22, 7), (24, 5)}

Answer 1

for a given x value, there cannot be two different y values. A, B,D clearly do not meet this criteria