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:

$\{(2,1),(1,3),(-5,9),(8,1)\}$

$\{(2,1),(-2,-1),(2,12),(4,7)\}$

$\{(9,-2),(4,13),(0,7),(3,13)\}$

$\{(7,-2),(2,9),(-1,6),(1,6)\}$

$\{(-5,10),(6,9),(7,-2),(6,5)\}$