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
Most severe luxation injury among the following: 
Select and explain. 
A. Concussion, B. Lateral luxation, C. Extrusion, D. Intrusion
D: Intrusion
Answer: D: Intrusion 
Explanation: order of luxation injuries on the basis of Severity:
Concussion<subluxation<lateral luxation<extrusion<intrusion