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
Test used for presence of residual helicobacter pylori infection 
Select and explain. 
A. Urease breath test, B. Rapid urease test, C. Gastric biopsy, D. Serological markers
A: Urease breath test
Answer: A: Urease breath test 
Explanation: Urease breath test is used for both diagnosis and eradication.