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: Microbiology
True about Helicobacter pylori is - 
Select and explain. 
A. Culture and gram staining of biopsy is the gold standard investigation, B. Controlled urea breath is negative with massive infection., C. Anti urease antibody are produced only by invasive strains, D. Urease activity provides protective environment to the bacilli.
D: Urease activity provides protective environment to the bacilli.
Answer: D: Urease activity provides protective environment to the bacilli. 
Explanation: None