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: Skin
[{'content': 'In congenital dystrophic epidermolysis bullosa defect is seen in: \nSelect and explain. \nA. Laminin 4, B. Collagen type 7, C. Collagen 4, D. Collagen 3', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B. i.e. Collagen 7', 'role': 'assistant'}]