Final answer:
Option c. 'Rotavirus or noroviruses cause 90% of all cases' is the true statement regarding viral gastroenteritis, as these viruses are responsible for the majority of gastroenteritis occurrences and typically require rehydration therapy, not antiviral drugs.
Step-by-step explanation:
The correct answer to the question "Which of the following statements concerning viral gastroenteritis is true?" is option c. Rotavirus or noroviruses cause 90% of all cases of viral gastroenteritis. This is because these viruses are highly contagious and are especially common in infants, young children, and the elderly. They can cause a wide range of symptoms, including diarrhea, vomiting, and abdominal pain, but the condition is typically self-limiting and can be effectively treated with rehydration therapy. Viral gastroenteritis is a significant cause of morbidity and can be common in both developed and developing countries. Unlike bacterial infections, antimicrobial drugs are typically not used; thus, aggressive antiviral therapy is not needed for most cases of viral gastroenteritis, and the infectious dose of these viruses is relatively low as they can be highly infectious even in small quantities.