This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Arthritis, Subject name: Orthopaedics
Which is the most common joint involved in thalassemia? 
Select and explain. 
A. Hip, B. Knee, C. Shoulder, D. Ankle
B: Knee
Answer: B: Knee 
Explanation: Ans. B. Knee* Most common joint involved in thalassemia is Knee joint.* Most common orthopedic symptom in thalassemia is leg pain.