The correct answer is option 2: Fermentation. Fermentation is the process by which microorganisms, such as yeast or bacteria, convert organic compounds (such as sugars) into alcohol and carbon dioxide. This process occurs in the absence of oxygen and is commonly used in the production of alcoholic beverages, such as beer and wine. During fermentation, microorganisms break down the organic compounds through a series of enzymatic reactions, releasing energy and producing alcohol as a byproduct. This is different from combustion (option 1), which is a chemical reaction that occurs in the presence of oxygen, producing heat, light, and carbon dioxide. Anaerobic respiration (option 3) and aerobic respiration (option 4) are both metabolic processes that involve the breakdown of organic compounds, but they do not specifically result in the production of alcohol.