<prompt> A 1-year-old todler presents with a 2 day history of fever, vomiting, and watery, nonbloody diarrhea. On physical exam, she appears dehydrated. Which of the following best describes the most likely infecting organism?It has a complex double-stranded DNA genomeIt has a paially double-stranded circular DNA genomeIt has a segmented, double-stranded RNA genomeIt has a single-stranded circular RNA genome  <response>: Rotavirus is the most common cause of gastroenteritis in children between 3 months and 2 years of age. It is most prevalent in the winter. Rotavirus, one of the reoviruses, looks like a wheel which ROTAtes and possesses a double-shelled icosahedral capsid with no envelope. Its genome consists of 11 segments of double-stranded RNA. A complex double-stranded DNA genome is found in enteric adenoviruses, the third most common cause of gastroenteritis in infants and children. This organism possesses an icosahedral nucleocapsid. A paially double-stranded circular DNA genome is characteristic of hepatitis B. Its envelope contains surface antigen HBsAg. Its capsid is icosahedral and contains the genome along with DNA-dependent DNA polymerase, which also has reverse transcriptase activity. A single-stranded circular RNA genome is characteristic of hepatitis D virus. Its envelope consists of HBsAg. The virus is defective and is able to replicate only in cells infected with hepatitis B. 