Which of the following are infectious agents smaller than viruses?

They are pollution indicators and never grow in polluted areas.

Which statement is wrong about lichens?

Which of the following is the largest virus?

Which of the following is smaller than a virus?

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.