Which cargo is carried by a highway tanker that has a smaller-diameter tank with several reinforcing rings around the circumference?

The correct answer indicates that the highway tanker is designed to carry corrosives. Tankers that have a smaller diameter and are reinforced with rings are typically constructed to withstand the pressure and potential reactions associated with transporting corrosive materials. Corrosive substances can damage the interior of vehicles and materials not specifically designed to resist chemical degradation.

The reinforcing rings serve to enhance the structural integrity of the tank against the stresses that arise during transport, especially since corrosives may also be hazardous to the material of the tank itself if there were any leaks or spills. This design is integral to ensuring safety while transporting such hazardous materials.

In contrast, other cargo types such as flammable liquids, compressed gases, or bulk solids do not specifically require this type of tank design. Flammable liquids often necessitate special features to prevent ignition, and compressed gases require tanks that can withstand high pressures, usually with thicker walls rather than a smaller diameter. Bulk solids typically utilize different containment methods that do not depend on the specific structural characteristics associated with corrosive material containment.