Upon the mexicans cession, the united states found itself

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.

What factors influenced brazil's current and future economic strength?

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4