What ensures that you have no alcohol left in your body?

The assertion that you cannot have alcohol in your body once it has been metabolized focuses on the physiological process that occurs after consuming alcohol. When alcohol is ingested, the body metabolizes it over time through the liver. Thus, the idea is that, eventually, all alcohol will leave the system, as the body works to process and eliminate it.

In context, while measuring alcohol levels with a breathalyzer can provide an indication of whether alcohol is present at a given moment, it doesn't guarantee that there is no alcohol left in your body since the measurement is subject to time and individual metabolism. Drinking water can help with hydration but does not speed up the elimination of alcohol from the body. Therefore, time is indeed a critical factor; however, the focus of the correct option emphasizes the certainty that all alcohol will eventually be metabolized and eliminated, confirming the body's ultimate capacity to process it.