Which set of ordered pairs is a function

Question

(-1,5),(-1,4),(-1,3),(-1,2),(-1,1)
(-6,-4),(-4,-2),(0,0),(-4,2),(-6,4)
(-5,1),(-3,2),(-1,3),(1,4),(3,5)
(-2,1),(-4,2),(0,3),(4,1),(-2,5)

Answer 1

The set of ordered pairs that represents a function is:

(-5,1),(-3,2),(-1,3),(1,4),(3,5)