If a beverage has an alcohol by volume (ABV) of 20%, what is its proof?

To determine the proof of a beverage based on its alcohol by volume (ABV), you multiply the ABV percentage by 2. In this case, with an ABV of 20%, you would calculate the proof as follows:

20% ABV × 2 = 40 proof.

This conversion is a standard method used in the United States to express the alcoholic strength of a beverage. It's important to note that proof is a measure that reflects the total alcohol content, with the proof number being twice the percentage of ABV.

By correctly calculating and applying this formula, it becomes clear why the answer indicating a proof of 40 is accurate in this context. Other options do not align with this calculation.