In a healthcare environment, identifying who is impacted during a critical incident is essential to patient safety and continuity of care. Within the Common Service Data Model (CSDM), the most effective way to determine impacted users is through Service Offerings, particularly when they are defined by department or location.

Service Offerings represent how a service is consumed by specific user groups. In this case, a patient management system may have different offerings for departments such as Emergency, Inpatient Care, or Outpatient Services, or be scoped by hospital location. These offerings explicitly define consumer context, allowing incident responders to immediately identify which clinicians, staff, or facilities are affected.

Option D (Affected CI related list) identifies technical impact but does not translate that impact into user or consumer context. Option A provides historical insight but does not identify current impacted users. Option C (service environment) helps differentiate production vs non-production but does not identify who is impacted.

By leveraging Service Offerings by Department or Location, the provider can quickly notify the right users, prioritize response based on clinical impact, and coordinate mitigation effectively—aligning with CSDM and ITIL best practices.

Therefore, the correct answer is B – Service Offerings by Department or Location.