Which document dictates the project scope but allows firm discretion on decisions?

The Request for Proposal (RFP) is the correct answer because it outlines the project scope while allowing the contractor or service provider the discretion to determine how to fulfill the requirements and specifications presented within it. An RFP typically serves to solicit bids from potential providers and includes details about the project's goals, budget, and timeline, but it does not dictate the exact methods or solutions to be used. This allows for a degree of flexibility for the responding vendors to leverage their expertise in crafting proposals that meet the outlined objectives while also taking into account their innovative strategies and approaches.

In contrast, the Scope of Work is more prescriptive, providing specific tasks and responsibilities that must be completed, while the Project Charter serves as an overarching document that defines the project's objectives and key stakeholders but does not provide flexibility in decision-making. The Business Plan outlines the overall strategy and financial plan for a business but is broader than a project-specific scope. Hence, the RFP's nature of defining scope with the allowance for discretion makes it the most suitable choice.