This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
[{'content': 'Which of the following are a Bacteria taxonomically? \nSelect and explain. \nA. Chlamydia, B. Rickettsia, C. Mycoplasma, D. Prion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Chlamydiae are obligate intracellular bacteria belonging to genus Chlamydia, in family Chlamydiaceae, under order Chlamydiales Ref: Textbook of Microbiology; Ananthanarayan and Paniker; 9th edition; Pg no: 415', 'role': 'assistant'}]