What do bottom side rails of a container support?

The bottom side rails of a container play a crucial structural role by providing support to the floor cross members. These cross members are critical components that ensure the integrity and stability of the container’s floor. They distribute the weight of the cargo evenly across the base of the container and contribute to the overall strength, preventing deformation or failure during transport.

Understanding this functionality is important for ensuring safe cargo loading and transport. By supporting the floor cross members, the bottom side rails help maintain the design specifications and safety standards required for shipping containers, making option B the correct choice. The roof panels, corner fittings, and top end rails have different roles and are supported by different structural elements within the container.