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': 'Oral ulcers that are painless are associated with \nSelect and explain. \nA. Secondary herpes, B. Primary syphilis, C. Tuberculosis, D. Primary herpes', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]