What does the term "proof" of an alcoholic beverage refer to?

The term "proof" of an alcoholic beverage is defined as double the percentage of alcohol by volume (ABV) in that beverage. For instance, if a beverage contains 40% alcohol by volume, it would be referred to as 80 proof. This method of measurement helps to convey the strength of an alcoholic drink in a way that is easily understandable.

In addition to indicating the potency of the beverage, the proof system has historical roots, dating back to the use of gunpowder for testing the alcohol content—hence the term. Other options listed do not relate to the definition of proof, as sugar content, carbon dioxide levels, and liquid volume do not account for the alcohol concentration within the beverage. Understanding the proof of a drink is essential for consumption awareness and responsible drinking practices.