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
Minimum thickness of calcium hydroxide required to protect near or actual pulp exposure is? 
Select and explain. 
A. 2-3 mm, B. 0.5-1mm, C. 3-4mm, D. 5mm
B: 0.5-1mm
Answer: B: 0.5-1mm 
Explanation: None