This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunomodulator, Subject name: Pharmacology
[{'content': 'Which is an immuno stimulant: \nSelect and explain. \nA. Methimazole, B. Levamizole, C. Ketoconazole, D. Zidovudine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: bRef: KDT, 5th ed, p. 763 & 4th ed, p. 821', 'role': 'assistant'}]