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

2, 3, 6 are objects having base but not upper lid.

1, 4, 7 tare objects which have neither a base nor an upper lid attached to them.

2, 3, 6 contain two similar elements one inside the other and both touching each other.

4, 5, 8 are divided into equal parts by straight lines emerging from the centre.

2, 5, 6 contain three elements (two of which are similar) placed one inside the other.

3, 7, 9 contain one element inside the other, which may or may not be similar.

3, 5, 6 are geometrical figures divided into two parts.

2, 4, 9 are geometrical figures divided into four parts.

3, 7, 9 are closed figures shaded by oblique line segments.

2, 4, 5 are figures composed of straight lines only.

2, 4, 7 are all divided into equal parts (either three or four parts) by straight lines and also have a black circle at the centre.

3, 5, 8 have similar designs and have their four corners shaded black.

2, 3, 4 contain straight lines each dividing, the figure into two equal parts.

7, 8, 9 have one element placed inside a different element.

2, 6, 9 have similar designs (three of the corners of the main figure are shaded black and there is a pattern formed around a '+' sign at the centre of the figure).

1, 4, 7 have similar designs (there are four small circles at(the corners of the main figure and there is a wheel shaped element at the centre of the figure).

4, 6, 7 are all closed figures touching a line segment.

2, 3, 9 are all closed figures intersected by a line.

6, 7, 8 have two different elements one placed inside the other.

1, 3, 5 have two different elements intersecting each other.