What holds the net upright and centered on a BAK-15?

The correct choice is the suspension system, as it plays a crucial role in keeping the net upright and centered on the BAK-15. In this context, the suspension system consists of various components that work together to provide stability and balance, ensuring that the net is properly aligned above the landing surface. This is essential for the net to function as intended, allowing for a safe environment for aircraft during landing rollouts.

The suspension system typically incorporates cables, rigging, or other structural elements that distribute the weight and forces acting on the net evenly. This system helps to absorb impacts, reducing stress and potential damage to both the net and the overall landing system. By allowing for some flexibility in its design, the suspension system also aids in adapting to various landing conditions.

Other elements, such as a framework system or support beams, may contribute to the overall structure of the BAK-15 but do not specifically address the function of keeping the net centered and upright like the suspension system does.