An individual shall not simultaneously hold what type of certification?

The correct choice indicates that an individual cannot simultaneously hold an inactive certification. In the context of EMS certification, an inactive certification means that the individual is not currently authorized to practice as an EMT or paramedic and has suspended their active certification status. This would prevent them from providing emergency medical services or functioning in their role as a certified practitioner.

By contrast, a national registry certification, dual citizenship, or a commercial driver’s license are entirely separate qualifications that do not inherently intersect with the operational status of an EMT's certification. An individual can hold a national registry certification while also having another certification as long as those certifications are active. Similarly, holding dual citizenship or a commercial driver’s license does not disqualify someone from being an EMT, as these do not relate directly to the professional practice of emergency medical services.

Understanding this distinction is essential for maintaining compliance within the field, ensuring that EMTs are actively certified when responding to emergencies.