What is the responsibility of the Army?

The responsibility of the Army primarily involves preparing land forces for military operations. This encompasses training soldiers, organizing combat units, and developing strategies to ensure that land forces are ready to defend the nation and accomplish designated missions. The Army's focus is on ground warfare, which includes artillery, infantry, armor, and support units that operate on land.

In contrast, conducting naval operations pertains to the Navy, which is responsible for maritime military actions. Managing space missions falls under the purview of organizations such as the U.S. Space Force, which handles space operations and assets. The oversight of budget allocations, while important for military management, is not a direct responsibility of the Army itself, as budget decisions typically involve higher levels of command and inter-service coordination. Thus, preparing land forces is the primary and defining responsibility of the Army, making the correct choice clear.