Primary containment refers to _____________ or other equipment intended to serve as the primary container for, or used for the transfer of, a material.

• A. transport vessels
• B. vessels
• C. pipes
• D. tanks

Answer: (B)

Primary containment is the container that directly holds a material or is used to transfer it. The term vessels covers that broad idea—the equipment designed to be the primary container for a material, including various forms like tanks and other containers used to hold or transfer the substance. Pipes, by contrast, are typically transfer lines rather than the primary container, and transport vessels refer to containers used specifically for moving contents, not the general notion of the primary containment. Tanks are a type of vessel, but using the broad term vessels correctly includes all such primary containers. So the best fit is vessels.