Coal
a)is a renewable energy source
b)is inorganic
c)releases fewer toxins than natural gas
d)produces almost half of our nation's electricity

The correct answer is D. produces almost half of our nation's electricity

The short answer is that is is D) produces almost half our nation's electricity. 

Coal is not a renewable energy source, once it is burned up, you cannot get it back. 
Coal is technically an organic source. It is made of plants and animals.
Also, coal releases millions of toxins every year, it's extremely harmful to our environment.