Match List-I with List-II:

List-I (Concepts)	List-II (Explanation)
(A) Standing state (B) Secondary productivity (C) Standing crop (D) Net primary productivity	(IV) Amount of mineral nutrients in the soil at a given time (II) Rate of formation of organic matter by consumers (III) Mass of living matter in a trophic level at a given time (I) Available biomass for the consumption of heterotrophs

Choose the correct answer from the options given below:

The correct option is (A)- (IV), (B)- (II), (C)- (III), (D)- (I).

Let us break down each concept from List-I and match it with its correct explanation from List-II step-by-step:

(A) Standing state matches with (IV) Amount of mineral nutrients in the soil at a given time:
In an ecosystem, the standing state refers to the total amount of inorganic nutrients (such as nitrogen, phosphorus, calcium, etc.) present in the soil or abiotic environment at any given time.

(B) Secondary productivity matches with (II) Rate of formation of organic matter by consumers:
Secondary productivity is defined as the rate at which consumers (heterotrophs) assimilate energy and synthesize new organic matter in their bodies over a period of time.

(C) Standing crop matches with (III) Mass of living matter in a trophic level at a given time:
The standing crop represents the total biomass or mass of living organisms present in a specific trophic level at a particular time.

(D) Net primary productivity matches with (I) Available biomass for the consumption of heterotrophs:
Net Primary Productivity (NPP) is the remaining biomass or organic matter stored by primary producers (plants) after accounting for respiratory losses. This accumulated biomass is what is made available to heterotrophs (herbivores and decomposers) for consumption.

Matching these relationships together, we get:
(A) - (IV)
(B) - (II)
(C) - (III)
(D) - (I)