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
[{'content': 'Night guard bleaching refers to: \nSelect and explain. \nA. Laser activated bleaching, B. Dentist prescribed home applied technique, C. Thermobleaching, D. Photo bleaching', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Bleaching techniques\xa0\n\nFor vital teeth\xa0\n\n– Home bleaching technique/night guard vital bleaching.\n–\xa0In-office bleaching:\ni. Thermocatalytic\xa0\nii. Nonthermocatalytic\xa0\niii. Microabrasion.\xa0\n\nFor nonvital teeth\xa0\n\n–\xa0Thermocatalytic in-office bleaching\xa0\n–\xa0Walking bleach/intracoronal bleaching\xa0\n–\xa0Inside/outside bleaching\xa0\n–\xa0Closed chamber bleaching/extracoronal bleaching\xa0\n\nLaser-assisted bleaching.', 'role': 'assistant'}]