In the PMBOK® Guide, when a stakeholder requests a change—such as adding a new feature—the project manager must follow the established procedures for Integrated Change Control.

Why Choice C is correct:

The " Master " Document: The Project Management Plan is the primary document that defines how the project is executed, monitored, controlled, and closed. It contains several subsidiary plans that provide the specific " guidance " requested here.

Change Management Plan: Contained within the Project Management Plan, this sub-plan describes the formal process for submitting, evaluating, and approving or rejecting project changes.

Scope Management Plan: This sub-plan explains how the project scope will be defined, developed, and managed. It dictates how the team handles new feature requests to prevent scope creep.

Governance: The project management plan tells the stakeholder who has the authority to approve the feature (e.g., the Change Control Board or the Project Sponsor) and what forms or analysis are required.

Analysis of other options:

A and B (Release Plans): Whether for a product or a project, a release plan is a high-level timeline that shows when specific sets of functionality will be delivered to the customer. While it shows what is currently planned, it does not provide the process guidance for how to add something new.

D (Product management plan): This is a broader document focused on the entire lifecycle of a product (from conception to retirement). While relevant for a Product Manager, in the context of a specific project (which is a temporary endeavor to create a product), the " Project Management Plan " is the definitive source for operational guidance during the project life cycle.

Key Concept: The Project Management Institute (PMI) emphasizes that the Project Management Plan (Choice C) is the " playbook " for the project. It ensures that when a stakeholder wants to add a feature, they don ' t just tell a developer to build it; instead, they follow a structured, documented process that assesses the impact on the project ' s time, cost, and quality.