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': 'Mucosa is never involved in which of the following disorders – \nSelect and explain. \nA. Dermatitis herpetiformis, B. Pemphigus vulgaris, C. Epidermolysis bullosa acquisita, D. Toxic epidermal necrolysis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mucosal involvement\n\nCommon\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0→\xa0\xa0 Pemphigus\nRare \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0→\xa0\xa0\xa0Pemphigoid\nNot involved\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0→\xa0\xa0 Dermatitis herpetifo', 'role': 'assistant'}]