In the figure,the structure of an antibody molecule is shown. Name the parts $A$,$B$,and $C$.

Which type of cells produce an army of proteins to fight against pathogens that have entered our body?

$A$: Live attenuated vaccine is better in terms of immunity provided to the recipient.
$R$: As secondary lymphoid organs,example $Peyer's$ patches are stimulated to protect the individual.

In the case of tetanus,a patient is directly injected with antitoxins. This type of immunity is called .........

Differentiate between the following and provide examples for each:
$(a)$ Innate and acquired immunity
$(b)$ Active and passive immunity

Which of the following statements is incorrect?