Final answer:
The most appropriate action would be to obtain a CT scan of the head and neck.
Step-by-step explanation:
In this scenario, the most appropriate action would be to a. Obtain a CT scan of the head and neck. The patient is unresponsive and demonstrating abnormal flexion in response to pain, which indicates a potential head injury. A CT scan of the head and neck would provide important diagnostic information about any potential brain or spinal cord injury that may have occurred during the motor vehicle crash.