Which of the following types of stress-strain relationships best describes the behaviour of brittle materials, such as ceramics and thermosetting plastics? (^$\sigma$ = stress and ^$\epsilon$ = strain)

We know that brittle materials do not show elongation when external load is applied on them and they get altered by certain amount of load and thus, get cracked from unexpected points. The amount of ultimate load and point of fracture cannot be predetermined and elongation is also very, very less. These properties are best described by option (4).