O A. Vertical angles are congruent.
O B If two lines are parallel, then alternate exterior angles are congruent.
O C. If two lines are parallel, then alternate interior angles are congruent.
O D Corresponding angles theorem.
![O A Vertical angles are congruent O B If two lines are parallel then alternate exterior angles are congruent O C If two lines are parallel then alternate interi class=](https://us-static.z-dn.net/files/dcb/2d0cef173460fbf145491593fdf3aa7c.png)