em 1992 o brasil sediou a conferencia das nações unidas para o meio ambiente e desenvolvimento, no rio de janeiro, mais conhecida como rio-92 ou eco-92. Destaque qual a importância da ECO-92 para a sociedade e em que consiste a agenda 21

On this graph, the bottom horizontal line represents an ineffective price floor set above equilibrium. an effective price floor set below equilibrium. an ineffective price ceiling set above equilibrium. an effective price ceiling set below equilibrium.

How would i answer this for an exam?

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.