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 -a) Rotavirusb) RSVc) Herpesvirusd) Prion 
Select and explain. 
A. a, B. ac, C. ad, D. b
B: ac
Answer: B: ac 
Explanation: Rotavirus culture is difficult
So, electron microscopy is useful in diagnosis of Rotavirus infection
They characteristically appear as little wheels with short spokes radiating from a wide hub to a clearly defined outer rim.
The name Rota is derived from Latin word ‘rota’ means wheel.