Which stage is represented by the given figure?

How many sentences are correct?
$(1)$ The trophic levels in $GFC$ are unlimited.
$(2)$ Organisms at each trophic level depend on those at the higher trophic level for their energy demands.
$(3)$ Plants capture only $2-10$ percent of $PAR$.
$(4)$ All organisms are dependent for their food on producers, either directly or indirectly.

$A$ snake feeds on a rat,a hawk feeds on the snake,and the rat feeds on a grasshopper. In this food chain,what is the trophic level of the rat?

Amount of inorganic substances present in an ecosystem is . . . . . . Energy flow is a . . . . . . feature of ecosystem.

Pisaster is a . . . . . . .

Complete the following model of the carbon cycle by filling in $A, B, C, D, E,$ and $F$.