Which of the relations on {0, 1, 2, 3} is an equivalence relation?
1
{ (0, 0) (0, 2) (2, 0) (2, 2) (2, 3) (3, 2) (3, 3) }
2
{ (0, 0) (1, 1) (2, 2) (3, 3) }
3
{ (0, 0) (0, 1) (0, 2) (1, 0) (1, 1) (1, 2) (2, 0) }
4
{ (0, 0) (0, 2) (2, 3) (1, 1) (2, 2) }