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
Most common oncogenic RNA virus- 
Select and explain. 
A. Retrovirus, B. Picornavirus, C. Orthomyxovirus, D. Paramyxovirus
A: Retrovirus
Answer: A: Retrovirus 
Explanation: None