At which state does brittleness manifest in a material?

Brittleness in a material is characterized by its tendency to fracture easily without significant plastic deformation. This property means that when a material is subjected to stress, instead of deforming or stretching, it will break or shatter with little to no warning. Materials that are brittle do not absorb much energy before breaking, which is why they can fail suddenly under applied loads.

For example, brittle materials include glass and some ceramics, which can crack or snap when force is applied, highlighting their lack of ductility. This can occur even when the applied force is relatively low compared to the material's tensile strength. Therefore, option B is the most accurate description of when brittleness is observed, as it directly defines the material's inability to withstand forces without fracturing.