You are answering a USMLE-style medical question. Question: A 17-year-old male presents to the emergency department after a motor vehicle accident. The patient was an unrestrained driver in a head-on collision. He has a past medical history of asthma, depression, and anxiety. He is not currently taking any medications. His temperature is 99.5°F (37.5°C), blood pressure is 90/60 mmHg, pulse is 115/min, respirations are 22/min, and oxygen saturation is 99% on room air. The patient's cardiopulmonary exam is within normal limits. The patient is breathing on his own and has strong distal pulses. Ultimately, the patient is discharged with follow up instructions after no significant fractures or injuries are found. The patient then presents 4 months later to his primary doctor with weakness. The patient's strength in his upper extremities is 1/5. He has reduced sensation in his upper extremities as well. The patient's lower extremities reveal 5/5 strength with intact sensation. A chest radiograph and basic labs are ordered. Which of the following is the most likely diagnosis? Options: A) Cervical spine fracture B) Intracranial hemorrhage C) Syringomyelia D) Conversion disorder Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.