Final answer:
To indicate prior hepatitis B vaccination, the presence of HBsAb (hepatitis B surface antibody) in the blood test is the marker that suggests a successful immune response to vaccination.
Step-by-step explanation:
Among the markers detectable by a blood test indicating prior hepatitis B vaccination, the correct answer is HBsAb (hepatitis B surface antibody). After vaccination, the immune system produces these antibodies as a protective response to the presence of the hepatitis B surface antigen (HBsAg), a key component of the subunit hepatitis B vaccine. This vaccine is a non-infectious viral vaccine derived from HBsAg produced in yeast cells. Therefore, the detection of HBsAb in the blood indicates prior vaccination and immune system response to hepatitis B.