Where is the insignia worn on MC Service Dress Blues Alpha?

The correct choice is that the insignia is worn on both sleeves of the Marine Corps Service Dress Blues Alpha. In the Marine Corps uniform system, specifically for the Service Dress Blues, the distinctive insignia signifies rank and is prominently displayed on both sleeves. This placement allows for visibility and is part of the uniform's design to denote the wearer's rank clearly and formally during official functions and ceremonies.

In contrast, the insignia is not typically worn on the left sleeve, collar, or lower sleeves in this specific type of uniform. Each of these areas either has different insignias or is reserved for other elements of the uniform's decorum. This practice maintains a level of consistency and formality within the Marine Corps dress code.