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: Social & Preventive Medicine
All of the following statements regarding prevalence are true except 
Select and explain. 
A. It is proportion, B. Duration of disease effects prevalence, C. Numerator is a part of denominator, D. It is rate
D: It is rate
Answer: D: It is rate 
Explanation: Prevalence is a proportion with numerator being a part of denominator.
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.