The correct answer is option 3, which states that a virus is made up of nucleic acids (option 1) and proteins (option 3) only.
Nucleic acids are the genetic material of a virus and contain the instructions for replication and production of viral proteins. They can be either DNA or RNA.
Proteins are another essential component of a virus. They play various roles, such as facilitating viral entry into host cells, assembling new virus particles, and evading the host immune system.
Carbohydrates (option 2) are not typically found in viruses. Unlike cells, viruses lack the necessary enzymes for carbohydrate metabolism. Instead, they hijack the cellular machinery of their host to replicate and thrive.
In conclusion, a virus is composed of nucleic acids and proteins. Carbohydrates are not part of their structure.