Which reason completes the proof in the picture
A.alternate interior angles converse
B.opposite sides of a parallelogram are congruent
C.opposite angles of a parallelogram are congruent
D.alternate interior angles theorem
C. Opposite angles of a parallelogram are congruent.
Angle 1 is congruent to angle 2 because they are opposite angles of the larger parallelogram. Angle 2 is congruent to angle 3 because they are opposite angles of the smaller parallelogram.
