Viruses are known as:

$A$ scientist $X$ demonstrated that the extract of infected plants of $Y$ could cause infection in healthy plants and called the fluid as "Contagium vivum fluidum". Identify $X$ and $Y$.

In which plant is the microorganism shown in the given figure found?

Which is the first discovered virus?

$A$ virus with an icosahedral head and a helical tail is termed as:

Match the following:

Column $I$	Column $II$
$(a)$ Potato spindle tuber	$(i)$ Virus
$(b)$ Creutzfeldt-Jakob disease $(CJD)$	$(ii)$ Viroid
$(c)$ Cholera	$(iii)$ Prion
$(d)$ Leaf rolling and curling	$(iv)$ Bacteria