The correct option is C;
For us to prove that the two triangles are congruent by SSS, we must have it that all the sides of the two triangles are congruent
They both share AD, while the sides AB and AC are congruent
So what is left is to get a relation that would state that BD and DC are equal
The correct statement is the 3rd option
The third option clearly states the relation that all the related sides are congruent and we have the SSS congruency working out