What distinguishes a pressure tanker from a non-pressure tanker?

Answer: B — Pressure tankers are designed to handle gases and liquids under pressure

The correct answer highlights that pressure tankers are specifically engineered to safely transport gases and liquids that are under pressure. This design allows them to handle the unique requirements associated with pressurized materials, such as maintaining structural integrity and preventing leaks, which are critical for safety and compliance with regulations. Pressure tankers have reinforced structures, specialized valves, and fittings that enable them to contain substances that may expand, change state, or create gas under normal atmospheric conditions. This capability differentiates them from non-pressure tankers, which are not equipped to manage these types of conditions and typically transport liquids at atmospheric pressure. The other options do not accurately characterize the primary distinction between pressure and non-pressure tankers. Sizes can vary independently of the tanker type, non-pressure tankers can also be used to transport hazardous materials, and pressure tankers are not solely limited to liquid transport, as they may also carry gases safely.