Answer:
The combustion of fossil fuels such as coal and oil has raised the concentration of carbon dioxide in the atmosphere during the last century (CO2). This occurs because the combustion of coal or oil produces CO2 by combining carbon in the air with oxygen.
Your answer is C. the mushrooms were decomposing the dead tree logs :)<span />
Is there choices or no choices??
Carbon (C) is an element
Carbon Dioxide (CO2) is a compound
Hydrogen (H) is an element
Sodium Chloride (NaCl) is a compound
A good way to tell whether something is a compound or an element, is that in a compound there is a mixture of different elements. Like in Carbon Dioxide, the symbol is CO2. This shows the carbon (C) and oxygen (O) together. I hope i worded that well enough and this helps :)