Questions: All viruses are composed of at least nucleic acid covered by a coating comprised of

The answer is: protein.

Explanation:

• All viruses are composed of nucleic acid, which can be either DNA or RNA, and this nucleic acid is covered by a protective coating.
• This protective coating is known as a capsid, which is made up of protein subunits called capsomeres.
• The protein coat serves to protect the viral genetic material and aids in the attachment and entry of the virus into host cells.

In summary, the blank should be filled with "protein" as it is the material that forms the protective coating around the nucleic acid in viruses.