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
Denominator in specificity ? 
Select and explain. 
A. True positive, B. True negative, C. True positive plus false negative, D. True negative plus false positive
D: True negative plus false positive
Answer: D: True negative plus false positive 
Explanation: Ans. is 'd' i.e., True negative plus false positive