Which among the following is a secondary processing method that alters material shape or structure?

The process of altering a material's shape or structure is specifically associated with secondary processing methods, which are integral in preparing products for their final use after primary shaping methods like casting or machining.

The correct answer relates directly to altering material properties or dimensions during production. Secondary processing methods primarily focus on improving the functional attributes or finishing characteristics of a material after it has been initially shaped. For instance, conditioning or polishing might improve surface quality or aesthetics, but they do not fundamentally change the shape or structure of the material itself as secondary processing does.

Separating is aimed at dividing materials into smaller parts or different materials, which does not necessarily mean altering the shape or structure in the way that secondary processing implies. Therefore, while separating is a useful method within manufacturing, it is distinct from the intent of changing an existing structure, which is central to secondary processing methods.