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: Medicine
[{'content': 'A nursing student has just completed her hepatitis B vaccine series. On reviewing her laboratory studies (assuming she has no prior exposure to hepatitis B), you Expect: \nSelect and explain. \nA. Positive test for hepatitis B surface antigen, B. Antibody against hepatitis B surface antigen (anti-HBS) alone, C. Antibody against hepatitis core antigen (anti-HBC), D. Antibody against both surface and core antigen', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Antibody against hepatitis B surface antigen (anti-HBS) alonea. The current hepatitis B vaccine is genetically engineered to consist of hepatitis B surface antigen particles.b. Therefore, only antibody to surface antigen will be detected after vaccination.c. Since the patient has had no exposure to hepatitis B, she should be surface antigen-negative; surface antigen positivity means active disease, either acute or chronic.d. Patients who have recovered from hepatitis B have HBS ab and HBC ab.', 'role': 'assistant'}]