This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
[{'content': 'Tetracyclines are not useful for: \nSelect and explain. \nA. Trichomonas, B. Chlamydia, C. Syphilis, D. Rickettsia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a)chlamydial non specific urethritis(b)lymphogranulima venereum(c)atupical pneumonia(d)cholera(e)brucellosis(f)plague. (g)Relapsing fever*(h) Rickettsial infections: typhus, rocky mountain fever(i)syphilis ESSENTIALS OF MEDICAL PHARMACOLOGY page no.738', 'role': 'assistant'}]