What document formally outlines the required capabilities of a system?

The Capability Development Document (CDD) is the correct choice because it serves as a formal agreement that outlines the operational capabilities required for a system. It is essential in the systems acquisition process as it details the necessary functions and performance characteristics that the system must achieve to meet user needs. The CDD supports the planning, development, and evaluation phases of the acquisition process, providing a clear direction for systems engineers, project managers, and other stakeholders involved in the project.

The CDD enables the alignment of resources and technical efforts to deliver a system that meets specific mission requirements, ensuring that all parties understand what capabilities are expected and can work towards those objectives throughout the acquisition lifecycle. This makes it a vital document in ensuring the successful development and deployment of systems in military and defense contexts, as it helps prevent scope creep and miscommunication about system requirements.