A student was given the following diagram and asked to prove that 21 22. What would be the reason for the second step in the proof? Given: Line A and line Bare parallel. Prove: 21 22 2 3 Reasons Given Statements 1. Line A and Line Bare parallel 2. ZI5X3 3. 2523 4. 1322 O A. Alternating exterior angles are congruent. O B. Definition of supplementary angles C. Alternating interior angles are congruent. O D. Corresponding angles are congruent.