$X$-bodies are formed during the infection of:

Read the following statements carefully and identify correct statements $w.r.t.$ Lichens:
$a.$ The association cannot tolerate air pollution,especially due to sulphur dioxide.
$b.$ Lichens are annuals and their growth is slow.
$c.$ The fungal partner mostly belongs to Ascomycetes.
$d.$ Soredia are most efficient means of asexual reproduction.
$e.$ Orchids seldom occur without this association.
$f.$ Foliose lichens are pioneers of succession in a water body.

Assertion $(A)$: Viroids lack the protective protein coat known as the capsid.
Reason $(R)$: Viroids contain a short strand of $DNA$.

$A$: Viroids lack a protective protein coat called a capsid.
$R$: Viroids contain a short strand of $DNA$.

Match the Column-$I$ and Column-$II$:

Column-$I$	Column-$II$
$(i)$ Viroid	$(a)$ Ramachandran
$(ii)$ Cell	$(b)$ Leeuwenhoek
$(iii)$ Virus	$(c)$ $T.O. Diener$
$(iv)$ Triple helical structure of collagen	$(d)$ Ivanowsky

How is a bacteriophage known?