Concept:Starch is converted to ethanol by the action of microorganisms, which is fermentation.Explanation:Starch is first broken down into sugars, then yeast acts on the sugar to produce ethanol and carbon dioxide.The overall process is:C6H12O6yeast2C2H5OH+2CO2This biochemical conversion is called fermentation, not cracking, distillation, or oxidation.Answer:C. fermentation