Final answer:
The Long Spine Board is the best device for moving a patient with a suspected spinal injury as one single unit, providing rigid support and immobilizing the spine to prevent further injury.
Step-by-step explanation:
The BEST device for moving a patient with a suspected spinal injury as one single unit is the Long Spine Board. This device is specifically designed to provide rigid support to the entire body, immobilizing the spine and preventing further injury during transportation. It allows the patient to be securely strapped to the board, ensuring minimal movement of the spine. The Long Spine Board is commonly used by emergency medical services and healthcare professionals when transferring patients with suspected spinal injuries.