Answer:
Proof 2 would be correct
Explanation:
Angle 1 and Angle 2 are congruent with the corresponding angle are congruent theorem.
Angles 1 and 3 are congruence by a congruence theorem which states alternate interior angles are congruent.
Finally, angles 2 and 3 would be congruent since 1 and 2 are congruent and 1 and 3 are congruent so therefor, 2 and 3 would also be congruent. This is called Transitive property, it states if "a = b and a = c, then b = c "
Hope this helps!