Answer with explanation:
In Quadrilateral A B CD
Diagonal BD bisects angle D.
→→ ∠A DB=∠ C DB
In ΔA DB and ΔC DB
1. AB= CB→→→→[Given]
2. ∠A DB=∠ C DB-------[Given]
3. BD=BD ----[Common side]
⇒ ΔA DB ≅ ΔC DB→→→[S A S]
AD=DC→→→→[C P C T]
Option B:⇒ AD = DC