What properties are characteristic of a parallelogram?

A parallelogram is a type of quadrilateral that has specific properties defining its shape and behavior. The characteristic property of a parallelogram that makes choice A the correct answer is that opposite sides are both parallel and congruent. This means that not only do the opposite sides run alongside each other without intersecting, but they are also of equal length. This is a fundamental trait that distinguishes parallelograms from other quadrilaterals.

In addition to this property, parallelograms also have opposite angles that are equal, and adjacent angles that are supplementary. While some rectangles and squares fall under the broader category of parallelograms and do indeed have right angles, it is not accurate to say that all parallelograms have all angles as right angles, which is why that choice is not correct.

Similarly, stating that all sides are equal describes a specific type of parallelogram known as a rhombus but does not apply to all parallelograms in general. Additionally, saying that only one pair of opposite sides is parallel contradicts the very definition of a parallelogram, which requires that both pairs of opposite sides are parallel. Thus, the defining attributes related to the sides being both parallel and congruent firmly establish