Final answer:
At a BAC of 0.15%, the risk of causing a car crash increases significantly compared to driving sober, due to alcohol's impairment effects on judgment, coordination, and reaction time.
Step-by-step explanation:
When your Blood Alcohol Concentration (BAC) goes up to 0.15%, your chances of causing a car crash can become substantially higher compared to when you are sober. The exact multiplier for the increased risk can vary based on different sources, but it is generally accepted that impairment from alcohol significantly raises the likelihood of an accident.
The increase in risk is due to the effects of alcohol on the brain, impacting vital functions necessary for safe driving such as judgment, coordination, and the ability to react swiftly to changing situations on the road. It's essential for drivers to understand the serious risks associated with driving under the influence, as it not only endangers their own lives but also the lives of others on the road.