The u. s. transportation command, u. s. special operations command, u. s. strategic command and u. s cyber command comprise the: . geographic combatant commandsb. functional combatant commandsc. service component commandsd. functional component commands

The U.S. Transportation Command (USTRANSCOM),the U.S. Special Operations Command (USSOCOM),the U.S. Strategic Command (USSTRATCOM),and the U.S. Cyber Command (USCYBERCOM)

comprise the functional combatant commands (b).

The U.S. Department of Defense is composed of eleven combatant commands. Their mission is either functional, like the four commands listed above, or geographic. The seven geographic combatant commands are:

the U.S. Africa Command (USAFRICOM),the U.S. European Command (USEUCOM),the U.S. Indo-Pacific Command (USINDOPACOM),the U.S. Northern Command (USNORTHCOM),the U.S. Southern Command (USSOUTHCOM),the U.S. Central Command (USCENTCOM),and the U.S. Space Command (USSPACECOM).