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: Dental
A Female patient comes for treatment of discoloured maxillary canine tooth. On examination there is yellowish discoloration of tooth which is not tender on palpation or percussion test. Radiograph reveals obliteration of root canal. History of trauma is elicited on questioning.

What is the condition? 
Select and explain. 
A. Fibrous degeneration of pulp, B. Calcific metamorphosis, C. Pulp calcification, D. Dental fluorosis
B: Calcific metamorphosis
Answer: B: Calcific metamorphosis 
Explanation: None