❓ 题目 According to the passage, why is valuing regulating services more challenging than valuing provisioning services?
- A. A. They are less important for ecosystem stability.
- B. B. They lack visible economic benefits and are therefore ignored by policymakers.
- C. C. They operate over large scales and their marginal contributions are hard to isolate.
- D. D. They have clear market prices but are subject to frequent fluctuations.