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: Dental
[{'content': 'A most common cause of erythema multiforme – \nSelect and explain. \nA. Herpes simplex, B. DM, C. Pityriasis rosae, D. Erysipelas', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most of the cases of erythema multiforme are idiopathic, but amongst the known causes, HSV is the most important cause.', 'role': 'assistant'}]