Apair of parallel lines is cut by a transversal, as shown below:

I don't know what your choices are but they are alternate interior angles.  Alternate interior angles are congruent.

Step-by-step explanation:

Alternate interior angles are the angles at the different intersection along the transversal that are on opposite sides of the transversal and inside the parallel lines.

This is exactly what you have here, alternate interior angles are congruent when the the lines are parallel.

There are also alternate exterior.  These are at the different intersections along the trasversal that are opposite sides of the transversal but outside the parallel lines.

There is also corresponding angles.  I like to call these the copy and paste angles because when you copy one intersection and paste it over the other, the corresponding angles will be the ones that lay on top of each other.

There are also same-side interior angles. There are inside and on the same side of the transveral at the different intersections. These angles add up to be 180 degrees when the transversal cuts through parallel lines.