Which of the following best describes the term "unified command?"

The term "unified command" refers to a command structure that integrates military forces from multiple branches under a single leader to achieve a common objective. This ensures that the various service branches—such as the Army, Navy, Air Force, and Marine Corps—work together effectively and efficiently, leveraging their unique capabilities and resources to accomplish missions that span across different domains. The unified command structure enhances coordination and collaboration, facilitating a more streamlined approach to joint operations and strategic planning.

The other options do not distinctly capture the essence of unified command. It is not simply about operating independently (as indicated in the second option), nor is it only about operations in different geographic areas without the emphasis on joint leadership. The idea of collaboration among nations under national command authority refers more to coalition operations rather than the specific command structure that unified command describes.