Final answer:
Out of the options listed, 'medical direction' is one of the 10 system elements developed by NHTSA to sustain EMS systems, providing oversight for paramedics and EMS personnel.
Step-by-step explanation:
The 10 system elements developed by the National Highway Traffic Safety Administration (NHTSA) are designed to sustain Emergency Medical Services (EMS) systems. Among these elements, medical direction is one option listed. Medical direction typically involves oversight by a medical doctor, often referred to as the 'medical director.' Paramedics and other EMS personnel operate under the guidelines, protocols, and policies set forth by the medical direction they receive. This structure ensures coordinated and effective emergency medical care.