Which of the following is NOT a main type of container encountered by responders?

When considering the types of containers that responders typically deal with, it's essential to understand the classifications of hazardous materials containers and their purposes. Pressure containers, solid-holding containers, and cryogenic containers are all specific categories that serve distinct functions in the storage and transportation of hazardous materials.

Pressure containers are designed to hold gases or liquids under pressure, making them critical in scenarios involving chemicals stored at high pressures. Solid-holding containers are used for materials in solid form, which can include hazardous solids like powders or granules. Cryogenic containers are specialized for holding materials at extremely low temperatures, often used to store liquefied gases.

On the other hand, aerosol spray containers, while often used for various products such as cleaning supplies or personal care items, do not classify as a main type of container in the same way as those mentioned above. While they can pose hazards and responders must be cautious when handling them, they are typically considered a subcategory or specific use of pressure containers rather than a standalone main type. This distinction highlights why aerosol spray containers are not listed among the main container types encountered by responders in hazardous materials situations.