High-expansion foam is usually used for which of the following?

High-expansion foam is particularly effective in flooding large enclosed areas because it can rapidly expand to fill the space, displacing oxygen and suppressing potential fire hazards within that environment. This type of foam is designed to create a lightweight and highly expansive blanket that can address fires in warehouses, aircraft hangars, or other large structures where fire could be a significant risk.

In the context of the other choices, while high-expansion foam does play a role in various fire control strategies, its primary use is not suited for unignited fuel spills or transportation accidents where more targeted types of foam or other agents are preferable. Exposure protection can also employ different foam types that provide a more immediate barrier against flames, rather than the broad approach high-expansion foam offers. Therefore, the specific capabilities and intended applications of high-expansion foam make it the ideal choice for effectively managing and suppressing fires in expansive, enclosed environments.