9. In the figure below, Angle 1 is congruent to Angle 2.

What reason can be used to prove that mis parallel to n?

A. if a pair of verticals angles is congruent, then the lines forming them are parallel

B. If a pair of angles formed by a transversal is corresponding and supplementary, then two lines are parallel

C. If a pair of angles is congruent and the sum of their measures 180 degrees, then the line forming the angles are parallel

D. If two line are intersected by a transversal, and a pair of corresponding angles is congruent, then the two lines are parallel