In the PMBOK® Guide, when a change to the project scope is proposed, the project manager must understand the " rules " for how financial changes are handled.

Why Choice D is correct:

The Framework for Costs: The Cost Management Plan is a subsidiary of the project management plan that describes how the project costs will be planned, structured, and controlled.

Thresholds and Procedures: It establishes control thresholds, which indicate the amount of variance allowed before some action needs to be taken. It also outlines the processes for managing contingency reserves and how to request additional funding.

Decision Making: While the plan doesn ' t contain the specific dollar amounts (that ' s the budget), it tells the Project Manager how to determine if a budget can be adjusted, who has the authority to approve a budget increase, and the protocol for integrating new features into the financial baseline.

Analysis of other options:

A (Risk management plan): This plan describes how risk management activities will be structured and performed. While adding scope involves risk, this document doesn ' t provide the guidance on budget availability or financial control.

B (Cost estimate): A cost estimate is a quantitative assessment of the likely costs of the resources required to complete project work. It is a data point for a specific activity, not a management document that dictates how to handle budget changes for new features.

C (Risk register): This is a document where results of risk analysis and risk response planning are recorded. It would tell you if " scope increase " was an identified risk, but it won ' t give you the management procedures for budget allocation.

Key Concept: The Project Management Institute (PMI) emphasizes that you should always look to the " Management Plan " (Choice D) when the question asks how to handle a situation or where to find the rules for a specific project constraint. The Cost Management Plan ensures that any addition to the scope is evaluated against the financial health of the project in a disciplined, pre-approved manner.