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
Shade selection is done with in how much time to avoid fatigue of eyes? 
Select and explain. 
A. 5 seconds, B. 10 seconds, C. 15 seconds, D. 20 seconds
A: 5 seconds
Answer: A: 5 seconds 
Explanation: None