Answer:higher, O
Step-by-step explanation:
There is a higher propensity for gastric ulcers in people in the type _O_ blood group because an H. pylori lectin binds an oligosaccharide in the glycoproteins and glycolipids of that blood group.
This is because an H. pylori lectin binds an oligosaccharide in the glycoproteins and glycolipids of blood type Other than blood types AB or B.