This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscles of Lower Limb, Subject name: Anatomy
A healthy young athlete sitting at table with knee at 90deg flexion. What will happen when he fully extends the knee? 
Select and explain. 
A. Movement of tibial tuberosity towards medial border of patella, B. Movement of tibial tuberosity towards lateral border of patella, C. Movement of tibial tuberosity towards centre of patella, D. No change in relationship
B: Movement of tibial tuberosity towards lateral border of patella
Answer: B: Movement of tibial tuberosity towards lateral border of patella 
Explanation: In sitting posture (when foot is off the ground), full extension leads to knee locking (by lateral rotation of tibia). Hence, tibial tuberosity moves laterally towards the lateral border of patella.