The answer should be option B "<span>a parallelogram with all sides equal and all angles equal".
</span>Reason:
The answer is option B because a square is a parallelogram with all sides and angles equal. Its not option A because a square is not a polygon but does have equal sides. Its also not option C because a square is a rectangle but not a trapezoid therefore not combined. Its also not option D because its not a polygon but does have four sides which saying there not equal therefore not the answer.
I would say B) A parallelogram with all sides equal and all angles equal. Parallelograms aren't all squares. They can be rectangles and rhombuses. I would say B. They all have the same lengths on all sides. They all have the same angles as well. Take a look at the pictures below. They are all parallelograms. All sides are the same, and all angles are the same.