According to PRINCE2principles, the business case theme requires documenting the management actions necessary to ensure benefits are realized. This involves planning, measuring, and managing the realization of benefits, and it's critical for maintaining the relevance and justification of the project. References: PRINCE2 Foundation Handbook, Business Case Theme section.

Section: Volume B
Explanation/Reference:

Approved plans enable control primarily by defining what is included within the approved project scope, which helps to avoid scope creep. These plans establish clear boundaries and deliverables for the project, which are essential for managing resources and ensuring that the project team remains focused on delivering the specified outputs without unnecessary expansion of the project scope.References: (PRINCE2 7 Foundation Handbook, AXELOS)

The first task in PRINCE2's recommended approach to 'defining and analyzing the products' is writing the Project Product Description. This document outlines what the project must deliver in order to gain acceptance. It serves as the basis for defining and analyzing more detailed product descriptions later in the process. References: PRINCE2 7 Foundation Handbook and official training materials.