This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Pathology
Gene responsible for pathogenesis of H pylori 
Select and explain. 
A. Cag A, B. Cag B, C. Tax A, D. Hbx
A: Cag A
Answer: A: Cag A 
Explanation: Cytotoxic: products of two genes namely cytotoxin- associated gene A(cagA) and vacuolating agent(vacA) gene cause gastritis, peptic ulceration and cancer GENERAL AND SYSTEMIC PATHOLOGY RAMDAS NAYAK FIRST EDITION PAGE 379