Answer:
(B)the alternate interior angles theorem.
Step-by-step explanation:
The diagram for the question is attached below:
In the diagram:
BC is parallel to AD; and
AB is parallel to DC.
Effectively, the shape is a parallelogram.
The Alternate Interior Angles Theorem states that, when two parallel lines are cut by a transversal, the resulting alternate interior angles are congruent.
Therefore:
∠BCA ≅ ∠DAC and ∠BAC ≅ ∠DCA by the alternate interior angles theorem.
