A series of figures are given which can be grouped into classes. From the responses, select the groups into which the figures can be classified.

• 1, 4, 7; 2, 5, 8; 3, 6, 9
• 1, 4, 5; 2, 6, 8; 3, 7, 9
• 1, 7, 9; 3, 5, 8; 2, 4, 6
• 1, 6, 9; 2, 5, 8; 3, 4, 7