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: Microbiology
Patient presented with fever, coughing, headache. He developed rash on 3rd day, what is probable diagnosis ? 
Select and explain. 
A. Measles, B. Mumps, C. Small pox, D. Chicken pox
A: Measles
Answer: A: Measles 
Explanation: Ans. is 'a' i.e., Measles Measles - Rash appears 3-4 days after onset of febrile illnessMumps - There is no rashSmall pox - Already eradicatedChicken pox - Rash appears on day 1 of febrile illness.