Some effects of sulphur dioxide $(SO_2)$ and its transformation products on plants include:

Which of the following is associated with biomagnification?

What does '$X$' represent in the given figure?

Explain biomagnification and its effect in $DDT$.

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.

Thermal pollution of water bodies is due to