According to the PMBOK® Guide, the Project Management Plan is the primary document used to manage the project. It is a single, formal, approved document that defines how the project is executed, monitored, controlled, and closed.

Basis of All Work: The plan integrates and consolidates all subsidiary management plans and baselines (Scope, Schedule, Cost) into a cohesive whole. It acts as the " source of truth " for the team, ensuring everyone understands the methodology, the work to be done, and the processes for handling changes.

Execution and Performance: It doesn ' t just list what is being built; it explains how the project will be managed. This includes communication protocols, risk management strategies, and quality standards.

Living Document: While it is baselined, it is also progressively elaborated throughout the project life cycle, meaning it is updated as more information becomes available.

Why other options are incorrect:

Option B: Acknowledges the existence of a project and defines its high-level information: This is the purpose of the Project Charter, not the Project Management Plan. The Charter is a high-level document that precedes the detailed planning phase.

Option C: Authorizes the project manager to apply organizational resources to project activities: This is also a key function of the Project Charter. Without a signed Charter, a Project Manager has no formal authority to spend money or assign staff.

Option D: Provides the project manager with organizational standards, policies, processes, and procedures: These are known as Organizational Process Assets (OPAs). While the Project Management Plan incorporates these standards, it is not the source of them; rather, it uses them as inputs to create the project-specific strategy.