What are three ways of intervening to prevent a friend from driving under the influence?

Choosing to stop serving alcohol, ensuring time for the body to metabolize alcohol, and taking the person's keys are effective interventions to prevent someone from driving under the influence.

When you stop serving alcohol, you're directly addressing the source of impairment. Many individuals may not recognize their level of intoxication, so halting any further consumption can significantly reduce the risk of driving while impaired.

Providing time and food can help sober someone up, as food can slow the absorption of alcohol and give the body more time to process it. While this isn't a guarantee that they are fit to drive, it works to mitigate the immediate effects of intoxication.

Taking their keys is a proactive protective measure. This action removes their ability to drive altogether, acting as a safeguard against potential poor decision-making, especially if the individual feels capable of driving despite being under the influence.

The other options provided, while they may contain helpful suggestions, do not comprehensively address the most critical aspects of preventing someone from getting behind the wheel while impaired.