The figure below shows line r, points P and T on line r, and point Q not on line r. Also shown is ray PQ. Consider the partial construction of a line parallel to line r through point Q shown below. The final step of the construction is to dra a line through points Q and S. Once the construction is complete, which reason contributes to proving the validity o the construction? When two lines are cut by a transversal and the vertical angles are congruent, the lines are parallel. When two lines are cut by a transversal and the corresponding angles are congruent, the lines are parallel. Definition of an angle bisector Definition of a segment bisector