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
A twenty year old female patient comes to the clinic with discoloration of the upper right central incisor. This tooth was intact and otherwise asymptomatic.

The treatment most often employed for managing discoloration in a non-vital teeth is 
Select and explain. 
A. Microabrasion, B. Walking bleach, C. Over the counter bleaching, D. Veneer
B: Walking bleach
Answer: B: Walking bleach 
Explanation: None