Expression sets call decision matrices, which are tables that allow implementing of complex rules in a systematic, readable way. This answer fits because the requirement is about the specific platform mechanism named in the option, not a nearby workaround.
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. Build the Expression Set to call one or more Decision Matrices when the process needs complex, systematic, readable rules.
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 may look related, but it does not place the logic in the correct declarative Public Sector or OmniStudio configuration layer. D may look related, but it does not place the logic in the correct declarative Public Sector or OmniStudio configuration layer.
