What is the outcome when yeast ferments sugar without oxygen?

When yeast ferments sugar in the absence of oxygen, the primary outcome is the production of alcohol, specifically ethanol. This process is known as alcoholic fermentation, a metabolic pathway that yeast uses to convert carbohydrates (sugars) into alcohol and carbon dioxide. During fermentation, yeast cells metabolize the sugar and, as a byproduct, release alcohol and carbon dioxide gas. This reaction is widely utilized in the production of alcoholic beverages and in baking, where the carbon dioxide produced helps dough rise.

The other choices do not fully encompass the primary outcome of this fermentation process. While carbon dioxide is indeed produced during fermentation, it is not the main objective, and the absorption of carbon dioxide isn't relevant in this context. Heat may be generated as a byproduct, but it is not the singular outcome of the fermentation process. Additionally, the claim that all nutrients are lost does not accurately represent the fermentation process, as yeast also consumes sugars and other nutrients but does not result in complete nutrient loss. Thus, the correct answer focuses on the key outcome of alcohol production.