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': 'Incidence is: \nSelect and explain. \nA. That portion of population affected by a disease or other condition at a given time, B. Incidence is greater than prevalence, C. No. of new cases of a specific disease within a defined population over a period of time, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]