Which system of linear equations makes the sentence ture

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.

Where the main factor that enabled the growth of cities and civilizations was the existence of

Soil color only reflects the amount of organic matter present in soil.