This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'In doubtful cases, the presence of which organism confirms the fecal contamination of water- \nSelect and explain. \nA. Protozoa, B. Yeast, C. Clostridium perfringes, D. Fungi', 'role': 'user'}, {'content': "Answer: C \nExplanation: Park's textbook of preventive and social medicine 23rd edition. the presence of spores of Cl. perfringens in a natural water suggest that fecal contamination has occurred and their presence in the absence of coliform group suggest fecal contamination occurred at some remote time.", 'role': 'assistant'}]