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
Endontically treated posterior teeth are more susceptible to fracture than untreated one because: 
Select and explain. 
A. Loss of moisture., B. Hollow canals., C. Loss of coronal structure., D. All of the above.
C: Loss of coronal structure.
Answer: C: Loss of coronal structure. 
Explanation: None