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
Calcification of pulp: 
Select and explain. 
A. is in response to ageing, B. does not relate to the periodontal condition, C. precedes internal resorption, D. indicates presence of additional canal
A: is in response to ageing
Answer: A: is in response to ageing 
Explanation: None