What property describes a material's ability to be stretched and reduced in cross-section without breaking?

The ability of a material to be stretched and reduced in cross-section without breaking is primarily referred to as ductility. Ductile materials can undergo significant plastic deformation before rupture, allowing them to be drawn into wires or stretched without failing. This property is crucial in various engineering applications where materials need to withstand forces without breaking.

Elasticity, while related to deformation, primarily describes a material's ability to return to its original shape after the removal of a load. Toughness refers to a material's ability to absorb energy and deform plastically before fracturing, which encompasses both strength and ductility but does not specifically highlight the ability to elongate. Stiffness describes a material's resistance to deformation under load, but does not focus on the ability to stretch. Therefore, ductility is the most accurate term that captures the behavior of materials under tensile stress, emphasizing their capability to be molded and shaped without failing.