What does proof of a drink represent in relation to the alcohol content?

The concept of proof is used to measure the strength of an alcoholic beverage. In the United States, the proof value is defined as twice the percentage of alcohol by volume (ABV) that the beverage contains. Therefore, if a beverage has an alcohol content of 20% ABV, it would be labeled as 40 proof. This relationship is foundational for understanding how the strength of alcoholic drinks is quantified.

Choosing the option that states proof is twice the percent of alcohol matches this established definition, making it the correct choice. Understanding the proof system is important for responsible consumption and for recognizing the potency of different alcoholic beverages, which directly impacts decisions around alcohol use and driving safety.

The other choices do not align with the standard definition of proof in the context of alcohol measurement, as they suggest incorrect relationships between proof and alcohol content.