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
Enamel fracture without tooth structure loss or incomplete enamel fracture results from 
Select and explain. 
A. Concussion, B. Avulsion, C. Subluxation, D. Enamel infraction
D: Enamel infraction
Answer: D: Enamel infraction 
Explanation: None