Final answer:
In the U.S. military, SSG/E-6 and higher NCOs are appointed as battalion master drivers in writing by the Battalion Commander, who is responsible for assigning positions within their command.
Step-by-step explanation:
In the U.S. military, specifically for appointments within Army units, an SSG/E-6 or higher Non-Commissioned Officer (NCO) to the position of battalion master driver is usually appointed in writing by the Battalion Commander. The Battalion Commander holds the authority to assign duties and positions within their command. The master driver is responsible for overseeing driver training and the maintenance of vehicle fleets within the battalion, ensuring that drivers are qualified and vehicles are ready for operational duties.