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: Pediatrics
An infant was brought to the casualty with complaints of watery diarrhoea and vomiting. He had mild fever. What is the MOST common cause of acute infantile gastroenteritis? 
Select and explain. 
A. Adenovirus, B. Norwalk virus, C. Rotavirus, D. Influenza virus
C: Rotavirus
Answer: C: Rotavirus 
Explanation: Viruses are the most common cause of acute gastroenteritis in infants. Of the viral agents causing enteric infection, rotavirus, a 67-nm double-stranded RNA virus with at least eight serotypes, is the most common. As with most viral pathogens, rotavirus affects the small intestine, causing voluminous watery diarrhea without leukocytes or blood. Rotavirus primarily affects infants between 3 and 15 months of age. The peak incidence in the winter. The virus is transmitted the fecal-oral route and survives for hours on hands and for days on environmental surfaces. Ref: Sundaram S.S., Hoffenberg E.J., Kramer R.E., Sondheimer J.M., Furuta G.T. (2012). Chapter 21. Gastrointestinal Tract. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.