Final answer:
Intermodal tanks can be both pressurized and non-pressurized, catering to diverse cargo needs. Gas generally moves from an area of high pressure to one of low pressure, following the basic principles of fluid dynamics.
Step-by-step explanation:
Intermodal tanks can be either pressurized or non-pressurized, so the correct answer is a. Both. These tanks are used for the transportation of various goods and can be designed to handle different types of cargo, including liquids, gases, and solids that may require a pressurized container or one that isn't pressurized at all. The design of an intermodal tank is highly dependent on the properties of the cargo it carries; for example, gases that are transported as liquids under pressure would require pressurized tanks, whereas non-hazardous liquids could be transported in non-pressurized tanks.
In the context of gas movement, a different principle applies. Gas will move from an area of high pressure to an area of low pressure, which aligns with the answer d. high; low for the basic concept of pressure gradients in fluid dynamics. This principle is fundamental to understanding how gases behave under different conditions, both in nature and in engineered systems.