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': 'Direct immunofluorescence(DIF) is negative in: \nSelect and explain. \nA. Bullous Pemphigoid, B. Cicatricial pemphigoid, C. Epidermolysis Bullosa Dystrophica, D. Pemphigus Folaceous', 'role': 'user'}, {'content': 'Answer: C \nExplanation: All of the above are autoimmune disorders except\xa0Epidermolysis Bullosa Dystrophica which is because of defective collagen.7 in dermis and hence DIF is negative.', 'role': 'assistant'}]