Questions: Which of the following is a valid reason why the quadrilateral shown below is a parallelogram? A. Both pairs of opposite angles are congruent. B. Both pairs of opposite sides are parallel. C. Both pairs of consecutive angles are complementary. D. Both pairs of consecutive angles are supplementary.

Solution Steps

A parallelogram is a quadrilateral with both pairs of opposite sides parallel. Additionally, in a parallelogram, opposite angles are congruent, consecutive angles are supplementary, and opposite sides are equal in length.

• Option A: Both pairs of opposite angles are congruent.
• Option B: Both pairs of opposite sides are parallel.
• Option C: Both pairs of consecutive angles are complementary.
• Option D: Both pairs of consecutive angles are supplementary.

The defining property of a parallelogram is that both pairs of opposite sides are parallel. This is the most direct and valid reason for the quadrilateral to be classified as a parallelogram.

Final Answer