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': 'Inveed fir tree appearance on gelatin stab is characteristic of? \nSelect and explain. \nA. Mycoplasma, B. Bacillus anthracis, C. Clostridium, D. Bacteriodes', 'role': 'user'}, {'content': "Answer: B \nExplanation: Virulent capsulated strains of Bacillus anthracis form rough culture, while avirulent or attenuated strains form smooth colonies. on gelatin stab culture, a characteristic 'inveed fir tree' appearance is seen with slow liquefaction commencing from the top. On blood agar the colonies are nonhemolytic though occasional strains produce a narrow zone of hemolysis .in broth growth occurs as floccular deposits with little or no turbidity REF:Ananthanarayan & Panicker's Textbook of Microbiology 8th Edition pg no: 243", 'role': 'assistant'}]