Business Rules Engine. This is the lowest-customization answer that still satisfies the business, security, and lifecycle requirements.
The Core Concept Explained: Business Rules Engine externalizes decision logic from custom code. Expression Sets orchestrate calculations and can call decision assets so policy thresholds remain maintainable by authorized business users.
Step-by-Step Technical Analysis: Identify the inputs that drive the decision, declare them as Expression Set resources, and use Decision Matrices or Decision Tables where business users must maintain rule thresholds. Execute representative samples before activation, then confirm the output and Decision Explainer history match the expected eligibility, fee, or prioritization result. Use Business Rules Engine to model qualification criteria, decision matrices, decision tables, and expression sets.
Why the Incorrect Options Are Wrong: A may look related, but it does not place the logic in the correct declarative Public Sector or OmniStudio configuration layer. B relies on older automation patterns that do not provide the same rule authoring, explanation, or industry metadata support required here. D adds a custom build path and increases lifecycle, security, and upgrade effort when a packaged or declarative capability already supports the requirement.