Final answer:
Rank insignia is the military uniform item not authorized for use with civilian attire, as it represents an individual’s official military position and could lead to misrepresentation.
Step-by-step explanation:
The military uniform item that is not authorized for use with civilian attire is a) Rank insignia. Military regulations typically prohibit the use of rank insignia on civilian clothes to avoid misrepresentation or the perception that one is on duty when they are not. While wearing military ID tags and certain unit patches discreetly may sometimes be allowed, name tags may also be restricted depending on the specific rules of the military branch. However, rank insignia is a distinctly military symbol that represents an individual’s official position within the armed forces and is therefore not permitted for use with civilian attire.