Final answer:
The 'envelope' of a virus may contain enzymes that facilitate the penetration of the host cell and is derived from the host's membrane structures. The envelope may also include glycoproteins aiding in attachment to the host cell.
Step-by-step explanation:
Viral envelopes can assist in the penetration of host cells. Specifically, they are derived from the host's membrane structures and often incorporate host cell phospholipids and proteins. Additionally, the envelope may contain viral glycoproteins and other proteins which can include enzymes instrumental in the infection process. Regarding the multiple-choice statements provided for context, the following information is accurate: Viral envelopes are derived from the host's membrane structures (B.), glycoproteins help the virus attach to the host cell (d.), and the viral capsid is composed of protein subunits called capsomeres (not capsids as stated in b.). To clarify, capsomeres cluster together to form the overall structure known as the capsid. It is also worth noting that not all viruses have a DNA genome; some, like HIV, have an RNA genome (c. is incorrect). Finally, mRNA functions within the host cell to produce proteins; it does not work outside the host cell (d.).