The answer is C. When there is combustion of a carbon-based fuel in a place with deficient oxygen levels, then the product would be high levels of carbon monoxide. If there is sufficient oxygen,then the product is carbon dioxide. This is illustrated by the equations below;
(Complete combustion) C8H18 + 2502 ----> 16CO2 + 18H20
(Incomplete combustion) C8H18 + 902 ----à C + 5CO + 2CO2 + 9H2O