Which type of blood test is specific for detecting Hepatitis B?

The correct choice for detecting Hepatitis B is HBsAg. This test specifically identifies the presence of the Hepatitis B surface antigen in the blood, which indicates an active Hepatitis B infection. The presence of HBsAg suggests that the virus is replicating in the body, and the individual is infectious.

Other tests mentioned, such as Anti-HAV, detect antibodies for Hepatitis A and are therefore not relevant for Hepatitis B detection. Anti-HCV tests are used to identify antibodies to Hepatitis C, and while Anti-HBs measures antibodies to Hepatitis B, it typically indicates recovery from the infection or vaccination rather than active disease. Therefore, HBsAg is the most direct indicator of an ongoing Hepatitis B infection.