Concept:Incomplete combustion occurs when there is insufficient oxygen for a fuel to burn completely.Explanation:A candle is mainly made of hydrocarbons.Under limited air, oxygen is not enough for complete combustion.Complete combustion would produce CO2 and water.Incomplete combustion instead produces carbon monoxide (CO) and unburnt carbon particles, known as soot.Therefore, the products are soot and CO.Answer:C. soot and CO