Answer:
The correct answer would be the virus envelope.
Viral envelope is a protective covering present around the capsid proteins in some viruses.
It is usually derived from the cell membrane of the host and thus it is composed of lipid and viral proteins.
It provides stability to the viral particle, helps in protecting the viral genome, and aids in the fusion of the virus with the membrane of the host.
Examples of viruses in which envelope is present: herpesviruses, poxviruses, flavivirus, hepatitis D et cetera.
Examples of viruses in which envelope is absent: adenoviridae , papillomaviridae , picornaviridae , caliciviridae et cetera.