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 disease does not occur as seasonal variation- 
Select and explain. 
A. Measles, B. Rubella, C. Gastroenteritis, D. None
D: None
Answer: D: None 
Explanation: Ans. d is None