In ServiceNow, controlling source precedence when multiple authorized data sources update the same CI attributes is a core responsibility of Identification and Reconciliation Engine (IRE) governance.

The correct and supported method is to assign priority to each data source in reconciliation rules. Reconciliation rules determine which source wins when multiple sources attempt to update the same attribute on a CI. By defining source precedence, the Configuration Manager ensures that the most authoritative system of record (for example, Discovery over manual imports, or HR systems over spreadsheets) consistently controls specific attributes or classes.

Option B is incorrect because manually sequencing data source runs is unreliable, does not scale, and violates Data Foundations best practices. Option C only controls how often data is refreshed, not which source is authoritative. Option D is incorrect because identification rules are used to uniquely identify CIs—not to control attribute-level precedence.

Using reconciliation rules provides deterministic, auditable, and automated control, which is essential for maintaining CMDB trust and avoiding data conflicts.

Therefore, the correct answer is A – Assign a priority to each data source in reconciliation rules.