What is an antibody?

Against which of the following does interferon act?

In the given figure,the part labeled as '$a$' represents:

Which of the following occurs in innate immunity?

Arrange the steps of the $phagocytosis$ process in the correct sequence.
$(a)$ Ingestion of microbes by phagocytes
$(b)$ Dilation of blood vessels by histamine
$(c)$ Formation of $phagosome$ and $phagolysosome$
$(d)$ Migration of phagocytes into $E.C.F.$
$(e)$ Attraction of phagocytes by $chemotoxins$ secreted by microbes
$(f)$ Intracellular destruction of bacteria

After infection of germs,the immunity acquired is: