Below is a two-column proof incorrectly proving that the three angles of δpqr sum to 180°: statements reasons draw line zy parallel to segment pq construction m∠zrp + m∠prq + m∠qry = m∠zry angle addition postulate ∠zrp ≅ ∠rpq alternate interior angles theorem ∠qry ≅ ∠pqr alternate interior angles theorem m∠rpq + m∠prq + m∠pqr = m∠zry substitution m∠zry = 180° definition of supplementary angles m∠rpq + m∠prq + m∠pqr = 180° substitution which statement will accurately correct the two-column proof? the measure of angle zry equals 180° by definition of a straight angle. angles qry and pqr should be proven congruent before the construction of line zy. the three angles of δpqr equal 180° according to the transitive property of equality. line zy should be drawn parallel to segment qr.