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
True about GIST are all,except : 
Select and explain. 
A. Most common site is duodenum, B. Well circumscribed, C. Ulceration and necrosis common, D. PET useful in predicting response to therapy
A: Most common site is duodenum
Answer: A: Most common site is duodenum 
Explanation: . Most common site is duodenum