How tall must the letters be on a sign indicating "UNREGULATED" services?

The correct height for the letters on a sign indicating "UNREGULATED" services is one inch. This specification is outlined in Minnesota state regulations, which aim to maintain visibility and clarity for consumers regarding the types of services being offered. Having a minimum letter height ensures that the information is easily readable from a distance, which is crucial for consumer awareness and safety.

Other options suggest taller letter heights, which exceed the minimum requirement set by the law. While clear visibility is important, the regulation determines that one inch is sufficient for effective communication. Therefore, the correct answer aligns with the established legal parameters governing signage in the context of unregulated services.