The diseases which occur at irregular intervals and locations are known as

Which type of diseases are restricted to the individual and do not spread to other individuals?

Statement $I$: $ELISA$ works on the principle of antigen-antibody interaction.
Statement $II$: Infection by a pathogen can be detected by the presence of antigens or by detecting the antibodies synthesized against the pathogen.

Match the following Column-$I$ with Column-$II$ and select the correct option.

Column-$I$	Column-$II$
$(a)$ Brown rust of wheat	$(i)$ Virus
$(b)$ Tobacco mosaic	$(ii)$ Bacteria
$(c)$ Black rot of crucifers	$(iii)$ Fungi
$(d)$ Red rot of sugarcane	$(iv)$ Insects

Megaloblastic anaemia of pregnancy is caused by the deficiency of

What was the major contribution of Louis Pasteur to the field of biology?