This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'The following is true about prevalence and incidence: \nSelect and explain. \nA. Both are rates, B. Prevalence is a rate but incidence is not, C. Incidence is a rate but prevalence is not, D. Both are not rates', 'role': 'user'}, {'content': "Answer: C \nExplanation: Incidence rate is defined as 'the number of NEW cases occurring in a defined population during a specific period of time.' Disease prevalence refers specifically to all current cases(old and new) existing at a given point in time or over a period of time in a given population. Although referred to as a rate, prevalence rate is really a ratio. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 68, 69", 'role': 'assistant'}]