This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Social & Preventive Medicine
Incidence of a disease is 4 per 1000 of population with duration of 2 years. Calculate the prevalence? 
Select and explain. 
A. 8/1000, B. 4/1000, C. 2/1000, D. 6/1000
A: 8/1000
Answer: A: 8/1000 
Explanation: Prevalence = (Incidence Rate) x (Average Duration of Disease)