Statement Reason 1. Quadrilateral PQRS is a rectangle. given 2. Rectangle PQRS is a parallelogram. definition of a rectangle 3. QP RS QR PS 4. mQPS = mRSP = 90 definition of a rectangle 5. PQS SRP SAS criterion for congruence 6. PR QS Corresponding sides of congruent triangles are congruent. 7. PR = QS Congruent line segments have equal measures. What is the reason for the third step in this proof? A. Corresponding sides of congruent triangles are equal in length. B. The diagonals of a rectangle bisect each other. C. SSS criterion for congruence D. Opposite sides of a parallelogram are congruent