Validating that case routing adheres to specific agent skill sets requires a multi-faceted approach. Manual testing of case assignments ensures real-world efficacy. Utilizing Process Builder and Flow triggers to trace case routing logic verifies the correct implementation of routing rules. Running Case Assignment Rule reports provides data-driven validation of routing accuracy. Hence, "D. All of the above, combined for a comprehensive validation of case routing logic and adherence to defined agent skill sets" best ensures that the system's functionality matches project requirements.
Reference: Salesforce Case Assignment and Routing