This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': "In Snyder's Test, the saliva is said to be highly cariogenic\nif colour change is observed at (hrs) \nSelect and explain. \nA. 24, B. 48, C. 72, D. 96", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]