A wire is stretched such that its volume remains constant. The Poission's ratio of the material
of the wire is

Poisson's ratio of a stable, isotropic, linear elastic material lies in the range $-1 < \sigma < 0.5$, theoretically. For most of the materials $\sigma < 0.5 .$ This is because, moduli of elasticity should have positive values. Negative Poisson's ratio in DESIGNED materials and in some anisotropic materials has been observed. $\therefore$ For most of the materials $\sigma < 0.5 .$ $\therefore$ option (B) is correct.