The statement about the polygons that is true is: "Each polygon has opposite sides that are parallel." Hence the correct option is a.
The statement "Each polygon has opposite sides that are parallel" is a fundamental characteristic of certain types of polygons. In geometrical terms, opposite sides refer to sides that are not adjacent but are connected by a diagonal. This property is notably true for parallelograms, rectangles, squares, and rhombi.
In a parallelogram, opposite sides are not only parallel but also equal in length. This is a defining feature of parallelograms. Rectangles, a specific type of parallelogram, further emphasize this characteristic, with all angles being right angles, ensuring that opposite sides are both parallel and equal.
A square, a subtype of rectangle, takes this concept a step further by having all sides equal in length, making all four sides parallel and identical. Similarly, a rhombus, while not necessarily having right angles, has all sides equal, guaranteeing parallelism between opposite sides. Hence the correct option is a.