Which materials can be used to construct step chocks for stabilization?

The correct choice is wood or plastic/composite blocks, as these materials are commonly used to construct step chocks for stabilization due to their favorable properties. Wood provides excellent strength and durability, making it capable of supporting the weight of the vehicle while preventing additional movement when placed under tires. Similarly, plastic or composite blocks can offer a lightweight, yet strong alternative that is often resistant to the elements, providing longevity in various environments.

Using step chocks made from these materials effectively helps in stabilizing vehicles during rescue operations, reducing the risk of additional injuries or complications. The design of these chocks can also accommodate different configurations based on the vehicle's size and the terrain.

The other options do not reflect practical or safe choices for constructing step chocks. Heavy metal could be cumbersome and difficult to position, while collapsible metal may not provide the adequate weight distribution or stability needed in a rescue scenario. Lastly, while the notion of using any rigid material seems broad, it does not ensure that the material will have the necessary properties to effectively stabilize a vehicle. Hence, wood or plastic/composite blocks are the most suitable and commonly accepted materials for this task.