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 determination of composite resin restoration on a tooth should be done; 
Select and explain. 
A. Before placement of rubber dam, B. On a dry tooth, C. Under bright light, D. Using a dry shade guide
A: Before placement of rubber dam
Answer: A: Before placement of rubber dam 
Explanation: None