This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Gram Positive Bacilli, Gram Negative Bacilli), Subject name: Microbiology
[{'content': "Filde's technique is used for- \nSelect and explain. \nA. Bacillus anthracis, B. Clostridium tetani, C. Mycoplasma pneumonia, D. Yersinia pestis", 'role': 'user'}, {'content': "Answer: B \nExplanation: Filde's technique is used for Cl. tetani. Cl. tetanihas the ability to swarm over the surface of medium. Because of marked tendency to swarm over the surface of the agar, surface colonies are difficult to obtain. Filde's technique: After incubating anaerobically for 24 hours, if the water of condensation at the bottom of a slope of nutrient agar is inoculated with a mixed cell culture, subcultures from the top of the tube will yield a pure growth of tetanus bacillus.", 'role': 'assistant'}]