What are viruses primarily composed of?

Viruses are primarily composed of nucleic acid and proteins. The nucleic acid can be either DNA or RNA, which serves as the genetic material for the virus. This genetic material carries the information necessary for the virus to replicate and produce new virus particles once they infect a host cell. The protein component of a virus is often organized into a protective coat known as a capsid, which helps to safeguard the nucleic acid and facilitate the virus's entry into host cells.

Unlike living organisms, viruses do not have cellular structures, organelles, or a cellular membrane. Instead, they are much simpler, relying solely on these two components—nucleic acid and proteins. This simplistic structure is key to their function and behavior as pathogens. By understanding that viruses lack cellular components and rely on their nucleic acid and protein for their life cycle, it becomes clear why option B is the accurate description of their composition.