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
Electron microscopy is helpful in diagnosis of ? 
Select and explain. 
A. Rotavirus, B. RSV, C. Herpesvirus, D. Prion
A: Rotavirus
Answer: A: Rotavirus 
Explanation: Ans. is 'a' i.e., Rotavirus