What is a characteristic of a parallelogram?

A parallelogram is defined as a four-sided figure (quadrilateral) where opposite sides are both parallel and equal in length. This characteristic is a fundamental property of parallelograms, stemming from the definition itself.

In a parallelogram, the opposite sides not only run parallel to each other but also share the same length, reinforcing the symmetry and balance within the shape. This aspect is essential in various geometric proofs and applications, establishing the foundational nature of parallelograms in the study of geometry.

While it's true that some parallelograms, like rectangles and squares, have right angles, not all parallelograms have this property. They don't necessarily feature all sides equal in length, as that characteristic specifically applies to rhombuses and squares. Furthermore, a parallelogram is characterized by having two pairs of parallel sides, rather than just two parallel sides. Thus, the distinguishing property of equal length in opposite sides makes the second characteristic the correct choice.