You are answering a USMLE-style medical question. Question: A 14-year-old boy presents to the emergency department with hand pain after falling from his skateboard one day ago. He reports that he lost his balance while attempting a new trick and fell on his outstretched hands. He has been icing his hand and taking several tablets of ibuprofen every few hours, but the pain and swelling have not improved. The patient reports that he has not been able to use the hand to take notes in school. His past medical history is significant for infectious mononucleosis last year and type 1 diabetes mellitus for which he has an insulin pump. On physical exam, there is mild swelling over the dorsal aspect of the hand and wrist. He has tenderness in the region between the extensor pollicus longus and the extensor pollicus brevis of the right hand. Which of the following is the best next step in management? Options: A) Radiograph of the wrist B) MRI of the wrist C) Thumb spica cast D) Radial gutter cast Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.