Given: line segment n m is parallel to line segment p o. and angle 1 is-congruent-to angle 3
prove: line segment n m is parallel to line segment n o.

4 lines are connected. line segment l m connects to line segment m n to form angle 1. line segment m n connects to line segment n o to form angle 2. line segment n o connects to line segment o p to form angle 3.

a 2-column table has 5 rows. column 1 is labeled statements with the entries line segment n m is parallel to line segment p o, angle 2 is-congruent-to angle 3, angle 1 is-congruent-to angle 3, angle 1 is-congruent-to angle 2, line segment l m is parallel to line segment n o.

what is the missing reason in the proof?

given
transitive property
alternate interior angles theorem
converse alternate interior angles theorem