What is a secondary securement procedure?

Answer: C — method for securing detached train parts

A secondary securement procedure specifically refers to measures put in place to secure detached train parts. When train components, such as cars or cargo, become disconnected or otherwise separated, it is crucial to ensure that these parts do not pose a hazard. The procedure involves additional steps to firmly secure these components to prevent rolling or shifting, especially in scenarios where gravity or movement could lead to accidents. This is instrumental for maintaining safety on the tracks, ensuring that all parts of the train system remain stable and under control, thus preventing potential accidents or injuries. In contrast, other options pertain to administrative or safety procedures that, while important for overall operations, do not focus specifically on the physical security of detached parts.