Group the given figures into three classes using each figure only once.

• A. 1,5, 6; 2, 3, 4; 7, 8, 9
• B.  1,4, 7; 2, 5, 8; 3, 6, 9
• C.  1, 2, 3; 4, 5, 8; 6, 7, 9
• D.  1, 3, 5; 2, 4, 8; 6, 7, 9