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
Koplik spot is pathognomic of which infection ? 
Select and explain. 
A. Rubella, B. Influenza, C. Mumps, D. Measles
D: Measles
Answer: D: Measles 
Explanation: Ans. is 'd' i.e., Measles