This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
[{'content': 'Avascular necrosis is the commonest in one of the following fracture - \nSelect and explain. \nA. Garden 1 and 2 fracture of femoral neck, B. Garden 3 and 4 fracture of femoral neck, C. Sub-trochanteric fracture of femoral neck, D. Baso-trochanteric fracture', 'role': 'user'}, {'content': "Answer: B \nExplanation: AVN and non-union are almost always seen with displaced fracture (Garden's III & IV) and are less common with undisplaced fractures (Garden's I & II).", 'role': 'assistant'}]