
Tajah-Rayne D. answered 05/17/20
Second Year Computer Science Major/Mathematics Minor
The answer is D: The Alternate Exterior Angles Converse Theorem.
This Alternate Exterior Angles theorem explains that if a pair of parallel lines are cut by a transversal, then the alternate exterior angles are congruent. Therefore, the converse of said theorem would be if the two exterior angles are congruent, then the lines cut by the transversal must be parallel.
Because the diagram shows that the exterior angles are congruent (both equal x) then that therefore proves that the lines are parallel.
Hope that helps!