The positive effect on the environment that the kyoto protocol intended to achieve? failed because developing countries were exempt. failed because the us did not sign the agreement. succeeded because overall emissions were reduced. succeeded because all countries signed the agreement.

The correct option is B.
The Kyoto Protocol was an an agreement which was negotiated by many countries in 1997. The major aim of the protocol is to cut down the emission of green houses gases which are causing global warming.
Part of the reason why the Kyoto Protocol failed is because, the USA did not ratify the agreement.