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
Which of the following will cause an increase in the prevalence of the disease - 
Select and explain. 
A. Immigration of healthy persons, B. Increased cure rate of the disease, C. Longer duration of the disease, D. Emigration of diseased persons
C: Longer duration of the disease
Answer: C: Longer duration of the disease 
Explanation: P = I x D
Increase in incidence or duration of disease results in increased prevalence.