Correct Answer - Option 1 : Square
Concept :
Square has all 4 sides equal. So it is having rotational symmetry at every ¼ th turn.
Rectangle has opposite sides equal. So it is having rotational symmetry at every ½ turn.
A regular hexagon has all 6 sides equal. So it is having rotational symmetry at every 1/6 th turn.
An equilateral triangle has all 3 sides equal. So it is having rotational symmetry at every 1/3 turn.
The correct option is 1 i.e. Square.