<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 21-year-old man comes to the military base physician for evaluation of progressive discomfort in his right shoulder for the past 4 months. He joined the military 6 months ago and is part of a drill team. In anticipation of an upcoming competition, he has been practicing rifle drills and firing exercises 8 hours a day. Physical examination shows tenderness to palpation and a firm mass in the superior part of the right deltopectoral groove. Range of motion is limited by pain and stiffness. Which of the following is the most likely diagnosis?? A: Osteoid osteoma, B: Lipoma, C: Acromioclavicular joint separation, D: Myositis ossificans, E: Arteriovenous fistula,  <response>: This is a clinical case question asking about the most likely diagnosis for a 21-year-old man with right shoulder pain and findings on exam after increasing his rifle drill and firing exercise. The key details are the progressive right shoulder discomfort over 4 months since joining the military and increasing drill practice, tenderness and mass in the deltopectoral groove, and limited range of motion. This indicates a likely overuse injury from repetitive motion. The choices given include both bone and soft tissue pathologies. Myositis ossificans involving heterotopic ossification is the most likely diagnosis given the clinical scenario of repetitive overuse injury.D: Myositis ossificans 