Which of the following sets of ordered pairs represents a function?
{(−4, −4), (−3, −3), (−2, −2), (−1, −1), (0, 0)}
{(−4, −4), (−4, −3), (−4, −2), (−4, −1), (−4, 0)}
{(−4, −4), (−4, 0), (−2, −3), (0, −2), (−2, −1)}
{(−4, −4), (−4, −1), (−2, −4), (−1, −4), (0, 0)}