Which shape always has opposite angles that are equal?

The choice of a parallelogram as the correct answer stems from its defining properties in geometry. In any parallelogram, opposite angles are always equal due to the way the shape is constructed. A parallelogram consists of two pairs of parallel sides, and the relationship between the angles occurs because each pair of opposite angles are congruent. This is a fundamental characteristic of parallelograms and holds true for all types of parallelograms, including rectangles and rhombuses.

Other shapes have distinct properties where this rule may not apply universally. For instance, while a square does have equal opposite angles, it is a specific type of parallelogram, making it an example of a larger category rather than a unique case. A trapezoid does not generally have equal opposite angles, since only one pair of sides is parallel, influencing the angle measurement. A circle does not have angles in the traditional sense, as it is defined by a continuous curve rather than angles formed by intersecting lines. Thus, the parallelogram stands out as the shape where opposite angles are consistently equal, regardless of its specific characteristics.