Answer:
B. capsid
Step-by-step explanation:
The capsid is closest in physical proximity to the nucleic acid of a virus. The capsid is the protein shell that encloses and protects the nucleic acid of a virus. It is made up of many protein subunits that come together to form a complex structure around the viral genome. The capsid can be thought of as a protective shell that shields the genetic material of the virus from the external environment and from host immune responses. The envelope and spikes are other components of some viruses, but they are located outside the capsid and are not in direct physical contact with the viral nucleic acid.