Robert Constant and his colleagues have put a price tag of ..US .33 trillion a year on

Options

A. Environment control
B. Ecosystem services
C. Ecological energy flow
D. Ecological succession

Answer

To solve the question regarding Robert Costanza and his colleagues putting a price tag of $33 trillion a year, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**:
- Robert Costanza is an American economist known for his work in ecological economics. He and his colleagues have focused on the value of natural resources and ecosystem services.

2. **Identifying the Price Tag**:
- The question states that Costanza and his colleagues have estimated a price tag of $33 trillion per year. This figure is significant and indicates a valuation of something important related to the environment.

3. **Exploring the Options**:
- The options provided (which are not listed in the question) likely relate to various environmental or economic concepts. We need to determine which of these options aligns with the $33 trillion valuation.

4. **Understanding Ecosystem Services**:
- Ecosystem services refer to the benefits that humans receive from natural ecosystems, such as clean air, water purification, pollination of crops, and climate regulation. Costanza and his colleagues emphasized the importance of recognizing these services in economic terms.

5. **Conclusion**:
- Based on the context and the work of Robert Costanza, the price tag of $33 trillion per year was placed on ecosystem services. This valuation aims to raise awareness about the importance of preserving natural resources for future generations.

6. **Final Answer**:
- The correct answer is **B. Ecosystem Services**.