TOEFL Listening: ETS-TOEFL听力机经 - XAA1Q836P1NA3FDHP$

Why does the man talk about the length of time it takes for a tree to grow? A. To explain why he thinks that tree maintenance is important to the benefit-based approach B. To suggest why the sales comparison approach is preferable to the benefit-based approach C. To raise a question about the accuracy of the benefit-based approach in determining the momentary value of trees D. To explain why foresight is needed to create an urban forest