A person should not smoke within ____ of a vehicle placarded for Class 3 or Division 2.1 materials.

You should not smoke within 25 feet of a placarded cargo tank used to transport materials that are categorized as Class 3 (flammable liquids) or Division 2.1 (gases). Do not smoke or carry a lit cigar, pipe, or cigarette near a vehicle containing flammable or explosive materials.