What is the primary characteristic of a brittle material?

Brittle materials are defined primarily by their failure characteristics, which include the tendency to fracture rather than deform under stress. When subjected to stress, brittle materials do not undergo significant plastic deformation; instead, they will break suddenly and without warning when the applied stress exceeds their inherent strength. This characteristic is critical because it differentiates brittle materials from ductile materials, which can absorb energy and undergo considerable deformation before fracturing.

The other characteristics listed in the answer choices describe attributes that do not align with the behavior of brittle materials. For instance, the ability to deform plastically before fracture is a hallmark of ductile materials, which allows them to absorb energy and avoid catastrophic failure. High tensile strength may be seen in both brittle and ductile materials, but it does not solely define brittleness. Additionally, while the ability to absorb shock is an essential characteristic of ductile materials, it does not occur in brittle materials, which would instead shatter under similar conditions. Understanding these differences is crucial in materials science and engineering applications, especially when selecting materials for specific uses where failure modes are a concern.