Below is a two-column proof incorrectly proving that the three angles of ? pqr sum to 180: statements reasons ? qry ? ? pqralternate interior angles theorem 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 m? rpq + m? prq + m? pqr = m? zry substitution m? zry = 180 definition of a straight angle m? rpq + m? prq + m? pqr = 180 substitution 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 after the construction of line zy.
c.) the three angles of ? pqr equal 180 according to the transitive property of equality.
d.) line zy should be drawn parallel to segment qr.