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 ulceration resembling apthae are encountered in \nSelect and explain. \nA. Gluten enteropathy, B. Chronic smokers, C. Excess of B-complex, D. Anti-malarial medication', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]