Determine which of the following relations is a function.

A.
X Y
-10 10
-5 5
0 0
5 -5
10 -10

B.
X Y
-3 2
-1 1
0 2
0 1
3 4

C.
X Y
-8 -4
-2 -2
1 3
2 4
4 6

D.
X Y
0 2
1 4
2 2
2 6
5 7