Final answer:
The correct action for an off-duty EMT witnessing a car accident is to stay with the patient complaining of neck pain until qualified personnel arrive, as per their ethical duty of care.
Step-by-step explanation:
When an EMT witnesses a car accident and someone is complaining of neck pain but other injuries appear minor, the EMT has an ethical duty to remain with the patient until emergency medical services (EMS) arrive and someone with equal or higher care level assumes care. Though the injury may seem minor, neck injuries can be serious and need proper assessment. Hence, the correct action would be to stay with the patient until someone with equal or higher care level assumes care (option D).
Leaving the patient because they are conscious and alert or because the injuries seem minor is against the duty of care expected from an EMT. While personal commitments are important, as an EMT, the immediate obligation is towards the patient in potential distress. The principles of prima facie duties suggest that the duty to help in an emergency situation would typically outweigh other commitments.