To prove that triangles \( \triangle ABD \) and \( \triangle DBC \) are congruent by the ASA (Angle-Side-Angle) Congruence Theorem, you need to establish two angles and the included side between those angles in each triangle.
Assuming that:
- You already have one angle from each triangle: \( \angle A \) from \( \triangle ABD \) and \( \angle D \) from \( \triangle DBC \),
- You also have the side \( AB \) which is shared between the two triangles,
you would require one additional piece of information, which would be a second angle in either triangle.
Therefore, the correct response from the options provided would likely be:
\( \angle A \cong \angle D \)
This would establish that you have the included side (AB) and the two angles (∠A and ∠D), satisfying the criteria for the ASA theorem.