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
Positive predictive value is most affected by ? 
Select and explain. 
A. Prevalence, B. Sensitivity, C. Specificity, D. Relative risk
A: Prevalence
Answer: A: Prevalence 
Explanation: Ans. is 'a' i.e., Prevalence