This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parasitology, Subject name: Microbiology
[{'content': 'Thick PBS is made for: \nSelect and explain. \nA. Speciation, B. Prevalance of parasite, C. Both speciation and prevalence, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Prevalence of parasite (Ref: D.R. Arora, 3rd/e)* Thin PBF - For Speciation.* Thick PBF - For Prevalence and Presence of Malarial parasites.", 'role': 'assistant'}]