Which relation is a function?
A {(-1,3), (-2,6), (0,0), (-2,-2)}
B {(-2,-2),(0,0), (1, 1), (2, 2)}
C {(4,0), (4,1),(4,2), (4,3)}
D
{(7,4), (8,8), (10, 8), (10, 10)}