If segment AB is congruent to segment CD and segment AB is parallel to segment CD, which of the following steps is not correct in proving that ABCD is a parallelogram? a If two parallel lines are cut by a transversal, the alternate interior angles are congruent. b SAS: If two sides and the included angle of one triangle are congruent to the corresponding parts of another triangle, the triangles are congruent. c Definition of perpendicular lines d CPCTC: Corresponding parts of congruent triangles are congruent.