a regular shape is a shape with equal side lengths & angles so the answer should be B
Figure A is regular polygon.
We are given four different figure. We need to select one regular figure.
Regular Polygon: It is figure whose sides, angles and exterior angles are equal.
Figure A: It is square of two dimensional figure. Square is regular figure.
It is regular polygon.
Figure B: It is shape of parallelogram whose opposite sides are parallel and equal. But adjacent sides are unequal. hence, It's not regular polygon.
Figure C: It is right angle triangle. Right angle triangle never be regular polygon. because all three sides are not equal.
Figure D: It is trapezoid. Trapezoid never be a regular polygon because their opposite sides never be equal.
Hence, Figure A is regular polygon.