Answer:
Coal puts out more Co2 emissions than Oil or Gas and Nuclear energy plants don't put out any pollution.
Step-by-step explanation:
Even though Coal is your answer it is actually a very clean form of generating energy. Not only is it very clean but it is the most effecient means. Solar and Wind power can't even come close to the production and turnover that Coal, Gas, and Oil can. Wind Turbines are so innefficent that they somtimes don't even pay off what it took to build them in thier lifetime of service. The production of Wind Turbines puts out more pollution than any of the Coal or Natural Gas Plants. Solar power is not very efficent either but it is on it's way. It is also very expensive.