Option C is correct. Best practices in economic capital frameworks and governance require a comprehensive contingency plan with clearly defined escalation procedures that are triggered when capital limits are approached or breached.

Option A is incorrect. Final approval for an internal economic capital model should come from independent model validation functions or senior risk management committees, not the business unit managers who stand to benefit directly from the model's output (conflict of interest). Option B is incorrect. Simply summing exposures across different risk types typically overestimates total risk as it ignores diversification benefits (assuming a perfect correlation of +1 across all risk types). Best practices include capturing diversification effects when aggregating economic capital. Option D is incorrect. The use of third-party macroeconomic scenarios is highly encouraged as an industry best practice for benchmarking and standardizing stress tests.