This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
A 15-year-old boy reports with a rapidly growing swelling of the mandible with intermittent pain. Patient history is that the swelling occurred after an episode of trauma. Radiographs reveal formation of new subperiosteal bone producing Onion Skin appearance. The patient also has lip paresthesia elevated white blood cell count
One of the following statements is true for Ewing's sarcoma 
Select and explain. 
A. An episode of trauma often precedes development of Ewing's sarcoma, B. Trauma is the main etiology in the development of Ewing's sarcoma, C. Relationship between trauma and Ewing's sarcoma has never been reported, D. Trauma can be considered as etiology for Ewing's sarcoma provided there is secondary infection
A: An episode of trauma often precedes development of Ewing's sarcoma
Answer: A: An episode of trauma often precedes development of Ewing's sarcoma 
Explanation: None