In the combustion reaction of butane, how many moles of carbon dioxide ... ...

In the combustion reaction of butane, how many moles of carbon dioxide are formed, if one mole of butane undergoes complete combustion in a controlled environment in the presence of excess oxygen?  
(A) one
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 15. Alkanes