Assertion: During succession, nutrient availability decreases while biomass levels increase.
Reason: NCP decreases during succession.
A.Both Assertion and Reason are correct and Reason is the correct explanation for assertion.
B.Both Assertion And reason are correct but Reason is not the correct explanation for Assertion.
C.Assertion is correct but Reason is incorrect.
D.Both Assertion and Reason are incorrect.

Hint: Ecological Succession is a process in which the change in structure of species of an ecological community takes over time. Succession if of two types-
1.Primary succession – In primary succession, a newly exposed or newly formed area is colonized by living things for the first time.
2.Secondary succession – In the case of secondary succession, an area which is previously occupied by living beings is disturbed or disrupted then recolonized .

Complete answer:
Assertion:
During succession, the nutrient availability increases while biomass level increases. Nutrient availability increases because more and more communities develop in the given area. When the community increases from a pioneer community to the climax community, the biomass will increase. His will increase the biomass because the number of organisms belonging to different species will also increase. Hence, the assertion is incorrect.
Reason:
NCP increases during the succession. NCP stands for Net Community Productivity. Net Community Production is the amount of organic matter in a particular trophic level. As the biomass is increasing, the level of carbon dioxide also increases which leads to the increase in Net community productivity. Hence, the reason is also incorrect.
Therefore, it has been clear from the above discussion that both assertion and reason are incorrect.

Hence the correct answer is OPTION(D)

Note: Biomass is made up of the material that comes from the living beings such as plants and animals. Biomass consists of plants, wood, waste of animals, etc. The energy produced by the biomass is called non renewable energy.