How many statements are correct?
$(a)$ Some animals like cockroaches,crows,etc.,are omnivores.
$(b)$ Detritus food chain $(DFC)$ begins with dead organic matter.
$(c)$ Each trophic level has a certain mass of living material at a particular time called as standing crop.
$(d)$ Species composition and stratification are two main structural features of an ecosystem.

In the dry weight of living beings,$A$ $\%$ carbon is present. In the oceans,$B$ $\%$ of the total global carbon is dissolved. The total amount of carbon in the atmosphere is $C$ $\%$ of the total global carbon. Identify the correct values for $A, B,$ and $C$.

Identify the correct type of food chain.
Dead animal $\rightarrow$ Blow fly maggots $\rightarrow$ Common frog $\rightarrow$ Snake

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.

Which stage is represented by the given figure?

Select the incorrect statement from the following.