Which of the following is an indicator of a sovereign citizen extremist?

The use of false license plates is a common indicator associated with sovereign citizen extremists. Individuals who identify with this movement often reject state authority and government regulations, leading them to create or utilize fraudulent documents as a means to assert their beliefs of independence from governmental jurisdiction. This behavior reflects their broader ideology, which includes a disdain for conventional laws and regulations considered valid by society.

The other options do not align closely with the defining characteristics of sovereign citizen extremism. While unique fashion statements, social media activism, and interest in community service may be observed in various groups or individuals, they do not specifically point to the identifying behaviors or beliefs characteristic of sovereign citizens. Thus, the specific act of using false license plates is a more direct and recognizable indicator of their ideology.