Which of the following materials has a good ductility property?

Ductility refers to a material's ability to deform under tensile stress, allowing it to be stretched into a wire or molded into various shapes without breaking. Softened brass demonstrates good ductility because it can be easily manipulated when heated, allowing for significant deformation while maintaining its strength. This quality is particularly advantageous in manufacturing processes, where ductile materials can be formed into complex shapes without fracturing.

In contrast, party balloons, while they can stretch to some extent, do not exhibit the same level of plastic deformation as metal alloys like softened brass. Plastic, though it can stretch and bend, often behaves more elastically and may not retain the same advantageous characteristics under mechanical stress. Glass, on the other hand, is brittle and does not exhibit significant ductility; it shatters rather than deforms when subjected to stress. Therefore, softened brass is the material among the choices that best represents good ductility.