In the given question, it is given that AB and DC are parallel and congruent.
So the reason for the first two statements are " Given" .
Third statement is angle BAC and DCA are congruent. And from the diagram, we can say that these angles are alternate interior angles. And alternate interior angles are congruent . So the reason is alternate interior angles postulate .
Fourth statement is AC and AC are congruent, and the reason is reflexive property .
And the final statement is triangles ABC and DCA are congruent, and the reason is SAS postulate .
