Question

Which of the following sets of ordered pairs is a function?

A. {(2, 1), (2, 2), (3,4), (5,6)}
B. {(-2,-1), (1, 2), (3, 4), (1,5)}
C. {(1,2), (2, 2), (3, 3), (2,4)}
D. {(1, 1), (2, 1), (3, 2), (4,4)}​

Answer 1

D

Explanation:

The other answers all have repeated x-values which would make them not functions.