What process is wrought metal subjected to during processing to enhance its properties?

The process referred to when discussing how wrought metal can enhance its properties is cold treatment, often known as annealing. This involves heating the metal to a specific temperature and then allowing it to cool slowly in a controlled environment. This treatment can reduce hardness and improve ductility, making the metal easier to work with.

In the context of wrought metals, annealing is especially important, as it can help relieve internal stresses and refine the grain structure of the metal. This results in improved machinability and formability, allowing the material to be better suited for various applications such as in construction, automotive, and aerospace industries.

Considering other processes listed: marbling is not a recognized process in metalworking, quenching refers to the rapid cooling of metal that typically increases hardness but may also lead to brittleness, and electroplating is a process used to coat the surface of a metal with a layer of another material, which isn’t directly aimed at enhancing the metal's inherent properties through structural changes. Thus, cold treatment or annealing stands out as the correct answer for improving the properties of wrought metal.