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
After enamel has been exposed to bacteria, irreversible bacterial colonization takes place in about 
Select and explain. 
A. 24 hrs, B. Few minutes, C. 1-2 hrs, D. 2-4 hrs
D: 2-4 hrs
Answer: D: 2-4 hrs 
Explanation: None