Ecology and Biodiversity

A cropfield ecosystem is an artificial agricultural ecosystem characterized by low biodiversity, minimal internal nutrient cycling due to human intervention and fertilizer input, and high net productivity subsidized by human labor and inputs.

An ecosystem consists of both biotic and abiotic components and interactions between them. When the interactions take place there must be some input of energy for example light energy is transferred to plants for performing photosynthesis and if there is an input of energy then there must be a continuous output of energy also.

an ecosystem includes both biotic and abiotic components of an area. Biotic components interact with their surroundings or the abiotic component to form a sustainable environment.

The ecosystem is a self-regulatory and self-sustaining structural and functional unit of the biosphere containing a community of living beings and the physical environment, both interacting and exchanging materials between them. In an ecosystem, energy flow is unidirectional. So, the correct option is "all of the above".

• Cropland includes areas used for the production of adapted crops for harvest. Two subcategories of cropland are recognized: cultivated and non-cultivated. 
• Cultivated cropland comprises land in row crops or close-grown crops and also other cultivated cropland, for example, hay land or pasture land that is in a rotation with row or close-grown crops.
•  Non-cultivated cropland includes permanent hay land and horticultural cropland. 
• Major natural resource concerns facing cropland include: (1) erosion by wind and water, (2) maintaining and enhancing soil quality, (3) water quality from nutrient and pesticides runoff and leaching, and (4) managing the quantity of water available for irrigation.
  

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. The Sun is the source of energy in most ecosystems. Energy is transferred from the Sun to plants that make their own food. The stored energy in plants is transferred to animals that eat the plants. When organisms die, their bodies decompose, or break down. The materials needed by organisms in an ecosystem are recycled, or used over again.  

Anthropogenic biomes, also known as anthromes or human biomes, describe the terrestrial biosphere in its contemporary, human-altered from using global ecosystem units defined by global patterns of sustained direct human interaction with ecosystems.

An ecosystem is not just an energy input system; it is a complex, self-regulating unit that involves the interaction of biotic and abiotic components. The claim that the only requirement is energy input ignores the necessity of nutrient cycling and biological interactions.

An ecosystem is fundamentally composed of two interacting parts: the biotic (living) community and the abiotic (non-living) environment.

Biotic factors refer to all living organisms in an ecosystem. Grass is a living plant, while water, sunlight, and oxygen are abiotic factors.

Nice is the ecological role and space that an organism fills in the ecosystem. The ecological niche involves both the place where an organism live and role that an organism carries out in its habitat e.g. A plant growing in garden along with soil, climate, sunlight, nutrients etc.

Forests provide excellent introduction to the foundational concepts of ecology, since they are among the most structurally and biologically diverse of the planets ecosystems. Forests are built upon highly complex relationships between living and non-living components. In a forest, abiotic factors include fundamentals such as sunlight, moisture, nutrients, bedrock and topography. Biotic components are the living members of the system. A defining trait of an ecosystem is the cycling of nutrients and energy between organisms and their environment, and it is these abiotic components that provide the foundation for interaction between members of ecological communities. 

Living organisms constantly take in or give out various abiotic factors. Thus, each biotic factor affects the quality of the abiotic factor around itself and thus affects the lives of the other biotic factors with which it share the ecosystem.

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. The fundamental source of energy in almost all ecosystems is radiant energy from the sun. The autotrophs processes the light energy and use the energy stored within the simple carbohydrates to produce the more complex organic compounds. The flow of energy through the ecosystem drives the movement of nutrients within the ecosystem. Decomposers play a key role in many of these cycles, returning nutrients to the soil, water, or air, where they can be used again by the biotic constituents of the ecosystem.

The biosphere is the world of living organisms together with soil layers (land or lithosphere), water (hydrosphere) and air (atmosphere) on the earth surface. Hence, it consists of 4 parts as land, water, air and living organisms. Of which  land, water and air are abiotic or non-living components and living organisms are biotic or living components. 
Producers are one of the type of biotic component, which produce their own food material from simple inorganic substances like $CO _2$ and water in presence of sunlight. E.g., Plants.
Consumers are one of the type of biotic component, which consume food prepared by producers. E.g., Human being, animals.
Decomposers are one of the type of biotic component, which derive their food material from dead, decaying matter. Eg. Bacteria, fungi.
Hence, option A, B and C are incorrect. 
Air is a abiotic or non-living type of component of biosphere. Therefore, option D is correct.