What is the process by which ethanol is legally made?

The process by which ethanol is legally made is fermentation. This process involves converting sugars, which can come from various sources such as grains, fruits, or sugarcane, into alcohol and carbon dioxide using yeast. During fermentation, the yeast consumes the sugars and produces ethanol as a byproduct. This method is not only the traditional method of producing alcohol but is also utilized in large-scale production for beverages and industrial applications.

The other processes mentioned do not represent the primary legal method for ethanol production. Distillation is a technique used to purify or concentrate ethanol after it has been produced through fermentation. Synthetization refers to the chemical process of creating ethanol from other substances, which may not be legally accepted in all jurisdictions for beverage production. Filtration is a method typically used in the purification or clarification of liquids and does not produce ethanol itself. Thus, fermentation remains the most recognized and legal process for the production of ethanol.