What is one of the major ways humans contribute to the concentrations of greenhouse gases in the atmosphere?

Question

a
by burning fossil fuels, like coal and natural gas, which release carbon dioxide into the air
b
by using electronics, like computers and televisions, which release ozone into the air
c
by damming waterways, like rivers and lakes, which release hydrogen into the air
d
by growing crops, like corn and beans, which release nitrogen into the air

Answer 1

a. by burning fossil fuels, like coal and natural gas, which release carbon dioxide into the air