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 immune response of hepatitis B is: 
Select and explain. 
A. Antibody of HBsAg is associated with resistance to infection, B. Antibody to HBc is not protective, C. Highest titres of anti-HBc are found in persistent carriers of HBsAg, D. CMI disappears soon after recover
A: Antibody of HBsAg is associated with resistance to infection
Answer: A: Antibody of HBsAg is associated with resistance to infection 
Explanation: Hepatitis B virus natural infection induces lifelong immunity.
The immunity is primarily mediated by humoral antibodies against HBsAg. Antibodies to HBsAg are protective. 
These antibodies bind to surface antigens or with the virus and prevent it from interacting with receptors on the hepatocytes.
These antibodies appear to neutralize the infectivity of HBV.

​Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:552