Which of the following is a producer in the plant kingdom?

Match the following Column-$I$ with Column-$II$:

Column-$I$	Column-$II$
$(i)$ Sedimentary cycle	$(P)$ Primary consumer
$(ii)$ Gaseous cycle	$(Q)$ Carbon
$(iii)$ Herbivore	$(R)$ Tertiary consumer
$(iv)$ Top carnivore	$(S)$ Sulphur

Some of the stages in the hydrarch succession are labelled as:
$I.$ Marsh meadow stage
$II.$ Reed swamp stage
$III.$ Submerged plant stage
$IV.$ Phytoplankton stage
$V.$ Submerged free floating plant stage
Identify the choice that represents the correct sequence of these stages.

Provide information about the aquatic weed known as the 'Terror of Bengal'.

Which of the following statements are correct regarding a food chain?
$(a)$ If $80\%$ of tigers are removed from an area,the growth of vegetation in that area increases.
$(b)$ If carnivores are removed from an area,the population growth of deer increases.
$(c)$ The length of a food chain is limited to $3$ to $4$ trophic levels because the amount of energy decreases in the ecosystem.
$(d)$ The length of a food chain is usually $2$ to $8$ trophic levels.

Identify the correct sequence of development of a stable community (climax community) starting from a new area (primary succession).