Final answer:
Sub-unified commanders and JTF commanders exercise Operational Control (B), which allows them to perform tasks and direct forces necessary for assigned missions, and sits between tactical and strategic control.
Step-by-step explanation:
The question pertains to the types of control exercised by sub-unified commanders and Joint Task Force (JTF) commanders. These commanders are responsible for conducting missions or operations generally overseen by a higher authority. In military parlance, the term 'Operational Control' (B) is the correct answer. This term signifies that commanders have the authority to perform tasks and direct forces necessary to accomplish assigned missions. It is less than full command, which encompasses strategic responsibility, but more than tactical control, which is limited to the deployment and maneuver of forces.
Operational control is distinct from tactical control, which is focused solely on the detailed and immediate direction and control of movements or maneuvers necessary to accomplish missions or tasks assigned by higher authority. Strategic control, on the other hand, often resides with the highest levels of military leadership and concerns itself with the overall strategy and policy direction of the military. Direct control refers to a hands-on management style, not a specific level of military authority.