burning candle

First of all, candle is an alkane with 28 carbons, i.e. C28H58.
For a such high ratio of carbon, the combustion is for sure to be sooty and yellow colour.
But it is worth to note that:

Incomplete combustion does not necessarily mean that carbon monoxide and/or soot must be produced. Sometimes it may produce black carbon powder.
Not only saturated hydrocarbons but also unsaturated hydrocarbons like alkenes and alkynes can also undergo incomplete combustion. The main reason for incomplete combustion is high ratio of carbon in the molecule rather than the type of compounds being burnt.
So overviewing all the answer, only D can be drawn as a conclusion.