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: Medicine
[{'content': 'All are true regarding Helicobacter pylori except \nSelect and explain. \nA. Less prevalent in developing countries, B. Toxicogenic strains usually causes ulcers, C. Urea breath test is positive, D. Gram negative organism', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]