The $D.P.T$ vaccine is an example of which type of immunity?

Innate immunity is characterized by:

The immunity acquired by the fetus from the mother through the placenta or by the infant from mother's milk for a short period is known as:

Interferons are a type of .........

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

Which of the following organs is a primary lymphoid organ?