Use the picture to answer the following question.



Which of the following statements BEST proves that lines k and m are parallel?
A. Angle 2 is congruent to angle 6 because corresponding angles are congruent if two parallel lines are cut by a transversal.

B. Angle 3 is congruent to angle 4 because supplementary angles are congruent if two parallel lines are cut by a transversal.

C. Angle 1 is congruent to angle 6 because alternate exterior angles are congruent if two parallel lines are cut by a transversal.

D. Angle 4 is congruent to angle 5 because alternate interior angles are congruent if two parallel lines are cut by a transversal.