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: Pathology
[{'content': 'Which of the following is not included under diagnostic criteria for NF - 1? \nSelect and explain. \nA. Optic glioma, B. Cafe - au - lait macules, C. periungual fibroma, D. Sphenoid dysplasia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Periungal fibroma is not included under diagnostic criteria for NF - 1.', 'role': 'assistant'}]