If three groups could be formed using the given figures only once, these groups would be ______ .
1
(2, 5, 7) (9, 6, 3) (7, 4, 1)
2
(1, 3, 8) (6, 7, 9) (5, 4, 2)
3
(7, 5, 2) (1, 8, 6) (4, 3, 9)
4
(1, 8, 6) (3, 5, 7) (4, 2, 9)
If three groups could be formed using the given figures only once, these groups would be ______ .