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
Rotavirus infection is diagnosed by the presence of- 
Select and explain. 
A. Antigen in stool by ELISA, B. Virus in stool, C. Antigen in blood, D. Antibody in stool
A: Antigen in stool by ELISA
Answer: A: Antigen in stool by ELISA 
Explanation: None