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

Concept

In figure-classification (grouping) questions, sort the given figures by the structural relationship between their internal elements, not by superficial appearance. Typical relationships include: two identical shapes nested one inside the other, two different shapes nested one inside the other, and a single shape drawn with a thick or shaded outline (visually two very close identical outlines with the gap between them filled in). Figures sharing the same relationship form one class, and every figure is used in exactly one class.

Application

1. Figure 1: an outer rectangle with an identical, smaller rectangle nested inside it — same shape nested in same shape.

2. Figure 5: an outer triangle with an identical, smaller triangle nested inside it — same relationship as Figure 1.

3. Figure 7: an outer parallelogram with an identical, smaller parallelogram nested inside it — same relationship again. So Figures 1, 5, 7 form one class.

4. Figure 2: a circle with a triangle (a different shape) nested inside it.

5. Figure 4: a square with a circle (a different shape) nested inside it — same relationship as Figure 2.

6. Figure 8: a triangle with a circle (a different shape) nested inside it — same relationship again. So Figures 2, 4, 8 form the second class.

7. Figure 3: a single triangle drawn with a thick, solid outline (as if two identical triangles almost touching, with the gap between them fully shaded).

8. Figure 6: a single circle drawn as a thick, shaded ring — same relationship as Figure 3.

9. Figure 9: a single square drawn with a thick, shaded border — same relationship again. So Figures 3, 6, 9 form the third class.

Cross-check

Each of the nine figures appears in exactly one class (1,5,7 / 2,4,8 / 3,6,9), and each class is defined by one consistent, clearly visible relationship, confirming the grouping is both exhaustive and mutually exclusive.

Result

The grouping 1,5,7 ; 2,4,8 ; 3,6,9 matches the correct option.