Answer: The answer is (b) Triangle ACD is congruent to triangle ABD.
Step-by-step explanation: In the given figure, ABC is a triangle, where the side AC is congruent to side AB.
ie., AC ≅ AB.
Now, vertex A is joint to a point D on BC. S, to prove ∠ABD ≅ ∠ACD, we need the two triangles, ΔABD and ΔACD to be congruent to each other.
Then, we can apply the rule that corresponding parts of congruent triangles are congruent, and we can conclude that
∠ABD ≅ ∠ACD.
The other three option will not serve our purpose.
Thus, the correct option is (b) Triangle ACD is congruent to triangle ABD.