Group the given figures into three classes using each figure only once.
A.
2,4,7 ; 1,8,9 ; 3,5,6
B.
2,6,9 ; 1,5,7 ; 3,4,8
C.
2,6,7 ; 1,5,8 ; 3,4,9
D.
2,8,7 ; 1,5,9 ; 3,4,6
Correct answer is B
1, 5, 7 contain a rectangle with its two diagonals as the outer element and another element (similar or different) placed inside it.
2, 6, 9 contain a triangle with its three medians as the outer element and another element (similar or different) placed inside it.
3, 4, 8 contain a circle with its two mutually perpendicular diameters as the outer element and another element (similar or different) placed inside it.