Why is the idea of common but differentiated responsibilities central in the Paris Climate Agreement?

Correct answer: Because all countries are involved but capacity and historical responsibility differ

The idea of common but differentiated responsibilities begins with a simple point: climate change affects all countries, so all countries need to participate in the response. However, countries do not have equal financial and technological capacity, and they have not contributed equally to historical greenhouse-gas emissions. Fair cooperation must therefore recognize both the common problem and these different circumstances.

The correct choice is A. This principle connects environmental cooperation with global justice. It does not claim that one country alone is responsible, that history is irrelevant, or that countries refuse to cooperate. Instead, it supports shared action while allowing responsibilities and support to reflect capacity and historical contribution. In climate diplomacy, this helps explain why developed and developing countries may be expected to make different kinds or levels of effort.