What is a breathalyzer?

A breathalyzer is a tool specifically designed to test a person's blood alcohol content (BAC) by analyzing their breath. When someone blows into the device, it measures the amount of ethanol in the breath, providing an estimate of their blood alcohol level. This measurement is crucial in law enforcement contexts, particularly for assessing whether a driver is over the legal limit for alcohol consumption, which helps maintain road safety.

The other choices represent different concepts but do not relate to what a breathalyzer does. For example, a device for measuring speed refers to tools like speedometers or radar guns, which monitor vehicle speed. A medicine to counteract intoxication would include substances that aim to sober someone up, which are not measured or assessed using a breathalyzer. Meanwhile, a software program for DUI prevention could suggest strategies for preventing drunk driving, but it doesn't actually perform the function of measuring BAC. Understanding the specific role of a breathalyzer emphasizes its importance in promoting responsible driving and reducing alcohol-related accidents.