Which of the following is used to remove particulate matter from industrial exhaust?

$B.O.D.$ is associated with:

Acid rain:
$(a)$ Causes necrosis
$(b)$ Converts chlorophyll-$a$ into phaeophytin
$(c)$ Responsible for formation of $PAN$

Observe the figure and answer the following questions.
$(i.)$ What ecological term is used to describe the $DDT$ accumulation at different trophic levels?
$(ii.)$ List any one effect of $DDT$ accumulation on birds.
$(iii.)$ Will $DDT$ accumulation lead to eutrophication?
$(iv.)$ Does it affect the $BOD$?
$(v.)$ Name a disease caused by the accumulation of any heavy metal.

Define $BOD$ (Biochemical Oxygen Demand).

What do catalytic converters convert unburnt hydrocarbons into?