Which of the following best describes toughness?

Toughness is characterized as the ability of a material to absorb energy and undergo plastic deformation before fracturing. This property is crucial in applications where materials are subject to impacts or stresses, allowing them to withstand sudden forces without breaking. Tough materials are typically those that can sustain significant deformation and energy absorption, such as metals that can be bent or stretched without snapping.

The other options describe different properties of materials. The ability to return to its original shape after deformation is related to elasticity, while resistance against wear and deformation pertains to hardness and abrasion resistance. The maximum stress a material can withstand without failure refers to its ultimate tensile strength, which does not account for the energy absorption capacity before failure. Thus, the description of toughness aligns directly with the first choice.