The correct option is 2: plan of action outlined by the countries of the world to combat climate change.

Intended Nationally Determined Contributions (INDCs) are pledges made by countries to reduce their greenhouse gas emissions and combat climate change. They were first introduced in 2015 as part of the Paris Agreement, a global treaty signed by almost all countries in the world to address climate change.

Each country was asked to submit its INDC, which outlines the specific actions the country will take to reduce its greenhouse gas emissions and adapt to the impacts of climate change. These contributions are "intended" because they are not legally binding, but countries are encouraged to set ambitious goals and regularly report their progress towards meeting them.

The purpose of the INDCs is to keep global temperature rise below 2 degrees Celsius above pre-industrial levels, and to pursue efforts to limit the temperature increase to 1.5 degrees Celsius. To achieve this, countries are expected to significantly reduce their emissions and shift to low-carbon, climate-resilient development pathways.

Therefore, option 2 is the correct answer as INDCs are directly related to the plan of action outlined by the countries of the world to combat climate change. Option 1 is incorrect as INDCs are not related to rehabilitating refugees. Option 3 is incorrect as INDCs are not related to the Asian Infrastructure Investment Bank. Option 4 is partially correct as INDCs are indirectly related to the Sustainable Development Goals (SDGs) as they contribute to Goal 13: Climate Action. However, it is not specific enough as INDCs are a distinct and separate plan of action from the SDGs.