What collar device does a Colonel in the Marine Corps wear?

A Colonel in the Marine Corps wears a silver eagle as their collar device. This insignia represents the rank of Colonel, which is the equivalent of the rank of 06 in the U.S. military rank system. The silver eagle is a distinctive and easily recognizable symbol that signifies authority and leadership within the Marine Corps.

The other options do not accurately represent the rank of Colonel. For example, the silver oak leaf is associated with the rank of Lieutenant Colonel, while the gold oak leaf symbolizes the rank of Major. The four silver five pointed stars represent the rank of General, which is significantly higher than Colonel. By understanding the insignia and their associated ranks, one can identify the hierarchical structure within the Marine Corps effectively.