Answer:
Alternate Interior Angles
Step-by-step explanation:
Since they are inside the parallel lines, Alternate Exterior Angles and any other similar theorems can be ruled out.
Since they are on opposite sides of each other, Corresponding Angles and any other similar theorems can be ruled out.
Since they are far apart from each other, Supplementary Angles, Adjacent Angles, Vertical Angles, and any other similar definitions can be ruled out.
Therefore, we are left with Alternate Interior Angles.