PLZ HELP ME GEOMETRY
question is below

For ΔABD, it is given that side AB is congruent to side CB, that ∠ABD is congruent to ∠CBD. In order to invoke the SAS Postulate, the remaining side(s) fo the triangles must be shown to be congruent. Those sides are BD and BD.
The appropriate choice is ...
... b. BD ≅ BD