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
[{'content': 'True about GIST are all,except : \nSelect and explain. \nA. Most common site is duodenum, B. Well circumscribed, C. Ulceration and necrosis common, D. PET useful in predicting response to therapy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: . Most common site is duodenum', 'role': 'assistant'}]