Question

under the kyoto protocol, developed countries took on a bigger share of limits, which led to
positive changes in the pollution levels worldwide.
increases in the participation of developing countries.
china becoming the leading producer of carbon dioxide emissions.
canada becoming the world leader in its lowered levels of pollution.

Explanation:

The Kyoto Protocol was an international treaty aimed at reducing greenhouse gas emissions. Developed countries had more stringent emission limits. However, some developing countries like China, which was not as restricted under the initial Kyoto Protocol (in its first commitment period), saw an increase in industrialization and thus became a major carbon dioxide emitter. The protocol didn't lead to positive worldwide pollution - level changes in the sense of overall global reduction as some countries didn't meet targets, and it didn't directly cause a huge increase in developing - country participation in the way of taking on similar strict limits as developed countries. Canada also did not become a world leader in pollution reduction under the Kyoto Protocol as it withdrew from the protocol.

Answer:

China becoming the leading producer of carbon dioxide emissions.