An Aggregate Group is the Business Rules Engine construct designed to repeat prior Expression Set logic for multiple input-value sets and then consolidate the resulting values. This matches a licensing scenario where one application contains multiple permits and the system must calculate a fee for each permit and then produce the total.

Salesforce explains that an Aggregate Group runs the preceding steps once for each input set and then applies aggregation logic to the results. Inside the Aggregate Group, the Aggregate step must be the first element and can perform SUM, AVG, MAX, or MIN calculations. Aggregate steps cannot exist independently outside an Aggregate Group.

Accordingly, the consultant first places an Aggregate Group at the appropriate point in the Expression Set and then adds an Aggregate step configured with the SUM function. If the rule calculates each selected permit's fee independently, SUM consolidates those calculated fee values into the total application fee.

A custom Lightning Component is unnecessary because Business Rules Engine already provides aggregation declaratively. Permission sets may be required to execute or administer BRE, but they don't implement the fee-calculation logic requested in the question.

Therefore, B and D represent the functional configuration required to support multiple selected permits and aggregate their calculated fees.

Study Guide Reference: Public Sector Solution Product Configuration – Business Rules Engine; Expression Sets; Aggregate Groups; Aggregate step; SUM function; multi-permit fee calculations.

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