A 23 year old medical student presents to the clinic complaining of right wrist pain after falling from his skateboard earlier in the day. He reports that he caught his fall with his outstretched right hand and he is now experiencing pain on a 7/10 scale. On physical examination there is swelling of his right wrist and tenderness over the anatomical snuff box. You order imaging of his wrist due to your concern that he has sustained a fracture of the wrist. Given the physical examination, which bone is most likely fractured