The correct option is "2 only." The Climate and Clean Air Coalition (CCAC) is indeed focused on addressing short-lived climate pollutants (SLCPs) such as methane, black carbon, and hydrofluorocarbons, which have significant impacts on climate change and air quality. However, it is not an initiative exclusively of the G20 group; it includes a broader coalition of governments, international organizations, businesses, and civil society. This differentiation is essential for UPSC as it highlights the collaborative nature of global environmental initiatives beyond specific groupings of countries.