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': 'The marker used for determining efficacy of Hepatitis B Vaccination is? \nSelect and explain. \nA. HBsAg, B. IgM anti HBcAg, C. IgG anti HBcAg, D. Anti HBsAg', 'role': 'user'}, {'content': 'Answer: D \nExplanation: ANSWER: (D) Anti HBsAgREF: APPENDIX-28 below for "MARKERS OF HEPATITIS-B""Positive Anti HBsAg determines the efficacy of hepatitis B vaccination" APPENDIX - 28Markers of Hepatitis-BWeeks after exposureTestsResultsInterpretationHBsAgAnti-HBcAnti-HBsNegativeNegativeNegativeSusceptibleHBsAgAnti-HBcAnti-HBsNegativePositivePositiveImmune due to natural infectionHBsAgAnti-HBcAnti-HBsNegativeNegativePositiveImmune due to hepatitis B vaccinationHBsAg Anti-HBc IgM anti-HBc Anti-HBsPositivePositivePositiveNegativeAcutely infectedHBsAg Anti-HBc IgM anti-HBc Anti-HBsPositivePositiveNegativeNegativeChronically infectedHBsAgAnti-HBcAnti-HBsNegativePositiveNegativeInterpretation unclear\' four possibilities:1. Resolved Infection (most common)2. False-positive anti-HBc, thus susceptible3. "Low level" chronic infection4. Resolving acute infection', 'role': 'assistant'}]