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: Skin
[{'content': 'Erythema nodosum is due to A/E: \nSelect and explain. \nA. Contraceptive pilles, B. Barbiturates, C. Penicillin, D. Sulphonamides', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Barbiturates', 'role': 'assistant'}]