An EMS unit is dispatched to a mass casualty incident along with police and fire...

When an incident involves multiple agencies with shared responsibility, NREMT teaches that a Unified Command structure is used. This allows police, fire, EMS, and other agencies to work together under a common set of objectives while maintaining their individual authority.

Option C is correct because the defining feature of unified command is multi-agency involvement, not rank or arrival order.

Option A is incorrect because no single agency automatically has authority.

Option B misunderstands unified command, which still functions with coordinated leadership.

Option D is incorrect because EMS does not automatically become part of command.

NREMT emphasizes unified command to improve coordination, communication, and safety during MCIs.