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: Medicine
HIV virus has : 
Select and explain. 
A. Single  stranded  DNA, B. Single  stranded  RNA, C. Double  stranded  DNA, D. Double  stranded  RNA
B: Single  stranded  RNA
Answer: B: Single  stranded  RNA 
Explanation: Classification of HIV ( = HTLV III) 
Family – Retroviridae
Subfamily – Lentivirus
Genome – SS RNA positive sense.
• Virion contain lipoprotein envelope and nucleocapsid is icosahedral in shape.
• Characteristic feature of retrovirus is presence of reverse transcriptase enzyme.
– Viral RNA is transcribed by this enzyme first into SS DNA then to ds DNA which gets integrated with host cell.
– Thus in contrast to central dogma flow of information is RNA  →  DNA  →  RNA