Each answer choice below represents a relation by a set of ordered pairs. In which of the answer choices is the relation a function? Select all correct answers.

Select all that apply:
{(9,−4),(−2,11),(−4,6),(9,−3)}
{(2,1),(−3,12),(6,12),(−2,−4)}
{(9,11),(6,−3),(7,4),(8,4)}
{(5,3),(9,7),(−1,2),(6,3)}
{(4,9),(2,−5),(−3,−4),(2,4)}