In this scenario, the most appropriate course of action would be:
B) Wait for the transporting EMS unit to arrive and take over care.
It's important to wait for the transporting EMS unit because they are trained and equipped to provide comprehensive medical assessment and care to the patient. While the patient complains of neck pain, conducting a full body examination (option C) could potentially worsen any injuries, especially if there is an underlying cervical spine injury. Requesting a helicopter transport (option D) should only be considered if there are clear indications of critical injuries or if ground transportation would result in a significant delay in reaching appropriate medical care. In this case, waiting for the transporting EMS unit ensures that the patient receives proper evaluation and care from trained professionals.