RNA retroviruses have an enzyme that

The correct option is C Transcribes viral RNA to cDNA
Transcription is a process where DNA gets transcribed to RNA. Retroviruses are viruses that are able to reverse transcribe their RNA genome into cDNA which is then integrated into a host genome. These retro viruses use their own enzyme called reverse transcriptase to produce DNA from its RNA genome which is the reverse of the usual pattern, thus retro (backwards). So the correct answer is 'transcribes viral RNA to cDNA'.