The correct answers are:
- develop renewable energy resources;
This will help significantly as it will move aside the usage of the fossil fuels which are one of the main sources of CO2 and methane in the atmosphere.
- improve agricultural methods;
By reducing the usage of the fossil fuels as well as chemicals in the agriculture can be lowered the emissions of methane and chemicals into the atmosphere.
- improve fuel efficiency in cars;
By improving the fuel efficiency in the the cars the result will be lesser usage of fuels in them which will give the same performances, so a win-win situation.
- reduce petroleum use;
Managing to reduce the usage or totally stop it of petroleum will stop huge amount of the CO2 emissions into the atmosphere.