The immune response provided by the body against pathogens with the help of $B$-lymphocytes is which type of immunity?

Which memory cells are produced during vaccination?

Which of the following are types of immunity?

Given below are two statements.
Statement $I$: Passive immunity is acquired when readymade antibodies are received by body cells.
Statement $II$: Resistance induced by $BCG$ vaccine is an example of passive immunity.
In the light of the above two statements,choose the correct answer from the options given below.

Which antibody is found in the highest concentration in the human body?

What plays an important role in primary and secondary response?