The rate of formation of new organic matter by rabbit in a grassland, is called.

Options

A. net productivity
B. secondary productivity
C. Net primary productivity
D. gross primary productivity.

Explanation

To solve the question regarding the rate of formation of new organic matter by rabbits in a grassland, we can break down the concepts step by step:

### Step-by-Step Solution:

1. **Understanding Productivity**:
- Productivity in ecological terms refers to the rate at which energy is converted into organic substances by producers and consumers in an ecosystem.

2. **Types of Productivity**:
- **Gross Primary Productivity (GPP)**: This is the total amount of energy captured by photosynthesis in a given area and time.
- **Net Primary Productivity (NPP)**: This is the energy that remains after the producers have used some of the energy for their own respiration. It represents the energy available to primary consumers.
- **Secondary Productivity**: This refers to the rate at which consumers (like rabbits) convert the chemical energy in their food into their own biomass.

3. **Identifying the Role of the Rabbit**:
- In this case, the rabbit is a **primary consumer** that feeds on grass (the producer). The organic matter formed by the rabbit is derived from the energy it obtains from consuming grass.

4. **Conclusion**:
- Since the question specifically asks for the rate of formation of new organic matter by the rabbit (a consumer), the correct term to describe this process is **secondary productivity**. This is because the rabbit converts the energy from the grass into its own biomass.

### Final Answer:
The rate of formation of new organic matter by rabbits in a grassland is called **secondary productivity**.

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