What is a feature of an MC 306/DOT 406 vessel?

An MC 306/DOT 406 vessel is specifically designed to transport liquids, particularly those that are non-pressurized and can include flammable liquids such as gasoline, diesel fuel, and other similar substances. This design incorporates a rounded shape, which helps to reduce stress and allows for easier loading and unloading of the liquid contents. The vessel is typically constructed to handle a variety of liquid materials, but its primary focus is on transporting flammable liquids, which aligns with its designation related to the transportation of liquefied materials.

Other types of vessels are specifically designed for different materials; for example, those that carry combustible solids or corrosives, as mentioned in the choices, have different structural features to accommodate the unique properties and hazards associated with those materials. Consequently, option C accurately conveys the primary use of the MC 306/DOT 406 vessel in transporting liquefied materials, particularly flammable liquids.