Answer:
D. proteins.
Step-by-step explanation:
The viral capsid comprises of proteins. The protein of the viral capsid are made up of proteins called protomers, this protomers are oligomeric sutructural subunits. It serves as the protein coating of the virus, and encloses the genetic material of the virus. Viral capsids are either isohadral or helical in structure.
The viral capsid, protects the viral genetic material from digestion enzymes, it has special site on the surface that aid the virus in attaching to the host cells and finally, it provides proteins for the virus to easily penetrate the cell memberane of the host.