Below is a two-column proof incorrectly proving that the three angles of ΔPQR add up 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 a Straight Angle
m∠RPQ + m∠PRQ + m∠PQR = 180° -Additive Property of Equality

Which statement will accurately correct the two-column proof?
A. The measure of angle ZRY equals 180° by definition of supplementary
angles.
B. Angles QRY and PQR should be proven congruent before the
construction of line ZY.
C. The three angles of ΔPQR equal 180° according to Substitution.
D. Line ZY should be drawn parallel to segment QR.