The treatment of snake bite by antivenom is an example of

Which type of immunity is acquired by intentionally introducing microorganisms into the body?

Select the $INCORRECT$ pair with respect to substances produced by cells involved in immune response.

Along with lymphoid organs,$WBCs$ are also present within the mucosa of digestive,respiratory,and excretory tracts as $MALT$,which constitutes about $.......$ of the total lymphoid tissue of the body: (in $\%$)

Define the following terms:
$(a)$ Immunity
$(b)$ Retrovirus
$(c)$ Allergy

Match the antibodies in List-$I$ with their respective functions in List-$II$.

List-$I$	List-$II$
$(a)$ $IgG$	$(i)$ Protection of body surfaces
$(b)$ $IgA$	$(ii)$ Regulation of allergic reactions
$(c)$ $IgM$	$(iii)$ Activates $B$-cells
$(d)$ $IgD$	$(iv)$ Protection of body fluids
$(e)$ $IgE$	$(v)$ Protection of blood circulation