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

1, 2, 5 are figures that have patterns formed from four lines curved in a concave direction.
3, 7, 8 are figures that have patterns formed from four lines curved in a convex direction.
4, 6, 9 are figures that have patterns formed from these straight lines.

3, 5, 8 have similar designs (four leaves placed close to a small circle and forming a symmetrical design at the centre of the figure).
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).

2, 4, 9 have two similar elements intersecting each other.
6, 7, 8 have two different elements one placed inside the other.
1, 3, 5 have two different elements intersecting each other.

1,6,9 are figures which are half shaded by slanting lines.

2,4,7 are all divided into equal parts (either 3 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.