A 12-year-old boy is brought to your office 2 days after a fracture of the humerus in its distal third. The patient complains that he is unable to extend the wrist. Which of the following structures was most likely damaged?
a. Median nerve
b. Ulnar nerve
c. Radial nerve
d. Axillary nerve
e. Artery supplying the brachial plexus