Which enzyme helps in the replication of viral $RNA$ genome into viral $DNA$ within macrophages?

Which one of the following produces $AIDS$?

Human immune deficiency virus $(HIV)$ is a retrovirus with centrally located two $ssRNA$ molecules. It is covered by an outer layer of $I$ protein and an inner layer made up of $II$ protein.

The virus responsible for $AIDS$ is an example of a(an):

At which stage of $HIV$ infection do the symptoms of $AIDS$ appear?

$A$ doctor,while operating on an $HIV$ patient,accidentally cut himself with a scalpel. He comes to you,suspecting that he may have contracted the virus. Which test will you advise him to perform to rule out or confirm his suspicion?