What action is considered illegal for drivers under the age of 21 in Iowa?

In Iowa, drivers under the age of 21 are subject to strict laws regarding alcohol consumption. The law states that any amount of alcohol in their system while operating a vehicle is illegal. This zero-tolerance policy is designed to promote safety and reduce the risk associated with underage drinking and driving.

This approach reflects the state's commitment to preventing alcohol-related accidents among younger drivers, who may be less experienced and more vulnerable to the impairing effects of alcohol. The other options, while they may carry restrictions for young drivers, do not directly relate to the prohibition of alcohol consumption when driving, making the action of driving after consuming any alcohol the only illegal activity specified in the scenario for this age group.