Why does land value gradually decrease from the main city center

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.

The coco river is a natural border between nicaragua and which other country

Can someone me? i need to have this done as soon as possible! i'm putting 20 points on this!