Which order provides an approved course of action and combat forces for planning purposes?

The correct answer identifies a crucial concept in military operations. An alert order is specifically designed to provide an approved course of action and the necessary combat forces for planning operations. This type of order serves as a signal to units that they should prepare for potential deployment or action, thus ensuring that the necessary resources and personnel are ready to be mobilized at a moment's notice.

The alert order facilitates strategic planning and readiness, allowing commanders to make decisions based on the forces currently prepared for action. This readiness is essential in maintaining operational effectiveness and responding promptly to changing situations on the ground.

In the context of the other options, the planning order typically lays out the details of the mission and coordinate efforts but does not necessarily mobilize forces for immediate action. Operational orders focus on executing specific missions but follow an approved plan after an alert order is given. Deployment orders involve the actual movement of forces to a designated area but come subsequent to prior orders, such as an alert order, indicating readiness and approval for action. Thus, while each order type plays a significant role in military operations, the alert order is distinct in its immediate purpose of readiness and course of action approval.