How does vaccination work

Options

A. The immune system produces antibodies which stay in the blood
B. Memory lymphocytes are produced. They remain in the body to fight off any future infection with the live pathogen
C. The dead pathogen stays in the body and constantly stimulates the immune system
D. All of the above

Answer

B

Explanation

A vaccine contains an antigen to which immune system respond. It contains attenuated antigen against which memory lymphocytes are produced and remain in the body for future encounter.