Which of the following could lead to serious legal consequences?

Exceeding a blood alcohol concentration of 0.2‰ is a significant legal concern because it directly impacts a person's ability to operate a vehicle safely. In Sweden, as in many other countries, there are strict laws regarding acceptable levels of alcohol in the bloodstream while driving. Being above the legal limit for blood alcohol concentration indicates impairment and increases the risk of accidents, which is why it is treated with strict legal repercussions. Pedestrians and other road users are at greater risk from impaired drivers, and as a result, the legal system imposes severe penalties, including fines, license suspension, and even imprisonment for severe violations.

The other choices, while potentially concerning from a safety perspective, do not carry the same level of legal ramifications. For instance, driving slightly under the speed limit is not a criminal offense, and driving in a restricted area with permission is compliant with regulations. Riding without a snowmobile helmet may increase the risk of injury, but it typically results in fines rather than serious legal consequences.