This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
Following a fracture of the humerus, which of the following is responsible for producing the majority of the new bone that will reunite the two fragments? 
Select and explain. 
A. Cancellous bone, B. Cailage, C. Compact bone, D. Periosteum
D: Periosteum
Answer: D: Periosteum 
Explanation: When the periosteum is torn during a fracture, it supplies cells that develop into osteoblasts and are the major producers of the new bone that reunites the two ends.