This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy and physiology of bone and fracture healing, Subject name: Orthopaedics
[{'content': 'Initial stage of clinical union of bone is equivalent to \nSelect and explain. \nA. Callus formation with woven bone, B. Woven bone Formation, C. Haematoma formation, D. Calcification formation only', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The first signs of union are seen in stage of hard callus formation A. Clinical sign:fracture is no more mobile B. Radilogical sign :callus is seen on X ray *hard callus is immature woven bone* Ref: Maheshwari 9th/e p 12', 'role': 'assistant'}]