The basic components of the ecosystem are

Options

A. Productivity and decomposition
B. Nutrient cycling
C. Energy flow
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding the Components**: The basic components of an ecosystem can be categorized into four main aspects: productivity, decomposition, nutrient cycling, and energy flow.

2. **Productivity**: This refers to the rate at which energy is produced in the ecosystem, primarily through photosynthesis. The energy produced contributes to biomass formation, which is essential for the growth of organisms within the ecosystem.

3. **Decomposition**: This is the process by which dead organic matter is broken down by decomposers, such as soil microbes. Decomposition is crucial for recycling nutrients back into the soil, enhancing soil fertility and supporting plant growth.

4. **Nutrient Cycling**: This involves the movement and exchange of organic and inorganic matter back into the production of living matter. Key cycles include the carbon, nitrogen, phosphorus, and sulfur cycles, which are vital for maintaining the balance of nutrients in the ecosystem.

5. **Energy Flow**: Energy flow describes how energy is transferred from one trophic level to another within the ecosystem. It is important to note that during this transfer, approximately 90% of energy is lost as heat, with only about 10% being passed on to the next level.

6. **Conclusion**: Therefore, the basic components of an ecosystem include productivity, decomposition, nutrient cycling, and energy flow. All these components work together to maintain the balance and sustainability of the ecosystem.