Answer:
B. viral reverse transcriptase to make a DNA copy that is integrated into the host genome and then host RNA polymerase transcribes it.
Step-by-step explanation:
RNA retrovirus when enters into its host cell it first use its reverse transcriptase enzyme and converts its RNA genome into the DNA so that viral DNA can be incorporated into the host cell and it can be replicated with the host cell.
One of the famous example of RNA retrovirus is HIV which infect CD4 cells and converts its RNA into cDNA with the help of reverse transcriptase enzyme and then this DNA enters the nucleus of the cell and incorporates into the host genome. Then it use host machinery to be transcribed. So the correct answer is B.