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: Radiology
[{'content': 'Hypoplastic defects in the enamel appears in radiographs as \nSelect and explain. \nA. Brown spots running horizontally, B. Radiotucent areas, C. Sclerotic areas over the surface of a tooth, D. Radio opaque areas', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]