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
Heywood and Heyman are associated with: 
Select and explain. 
A. Night guard vital bleaching., B. Walking bleach technique., C. Thermocatalytic technique., D. Microabrasion technique.
A: Night guard vital bleaching.
Answer: A: Night guard vital bleaching. 
Explanation: None