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
All of these are true for home bleach, except 
Select and explain. 
A. Dentist prescribed home technique, B. It contains 10-15% carbamide peroxide, C. Bleaching both arches at one time is preferred, D. Patient compliance is needed
C: Bleaching both arches at one time is preferred
Answer: C: Bleaching both arches at one time is preferred 
Explanation: None