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
Normal width of PDL is: 
Select and explain. 
A. 0.5mm, B. 1. mm, C. 1.5mm, D. 2. mm
A: 0.5mm
Answer: A: 0.5mm 
Explanation: None