Answer: 
The correct answer is option c. callus. 
Explanation: 
Callus in respect of osteology is the cartilaginous substance that makes the bridge that connects bone fracture during the repair of the fracture. Callus starts informing after a period of time of 1 to 2 weeks after the injury occurs on the bones. These initials callus are provisional callus that envelopes the site of fracture. 
Thus, the correct answer is option - callus.