Answer: The correct answer is -
Capsid (coat of protein).
Explanation:
All viruses (microscopic, acellular, non living organisms) form sheath of protein or a proteinaceous coat known as capsid, which surrounds the nucleic acid core (which may be DNA or RNA).
HIV (human immuno deficiency virus) has a RNA nucleic acid core that is single stranded and surrounded by a protein coat known as capsid.
Thus, capsid is the right answer.
