Which set of ordered pairs is a function?
A {(-1,5), (-1,4).(-1,3), (-1,2).(-1,1)}
B {(-6,-4).(-4,-2), (0,0).(-4,2).(-6,4)}
C {(-5,1). (-3,2).(-1,3), (1,4), (3,5)}
D {(-2.1).(-4,2), (0.3). (4.1).(-2,5)}