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: Surgery
All of the following predispose to gastric carcinoma except 
Select and explain. 
A. Achlorhydria, B. 'O'blood group, C. Pernicious anaemia, D. Post gastrectomy
B: 'O'blood group
Answer: B: 'O'blood group 
Explanation: None