Answer:
When two parallel lines are intersected by a transversal, the alternate interior angles are the pairs of non-adjacent angles that are located between the two parallel lines and on opposite sides of the transversal. These angles are congruent, which means they have the same measure. The other type of angles mentioned in the statement, which are supplementary, are the pairs of adjacent angles that are located on the same side of the transversal and outside the parallel lines. These angles add up to 180 degrees.
The correct choice is "consecutive interior angles are supplementary."