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.