Reasoning through Steps of a Proof
Given: m || CB
Prove: m∠ABC + m∠BAC + m∠ACB = 180°

Which statement justifies that angle XAB is congruent to angle ABC?

A) Corresponding angles of parallel lines cut by a transversal are congruent.
B) Vertical angles are congruent.
C) Same-side interior angles of parallel lines cut by a transversal are supplementary.
D) Alternate interior angles of parallel lines cut by a transversal are congruent.