The dimensions of Potsson's ratio is:
(a) $\left[\mathrm{M}^{0} \mathrm{~L}^{0} \mathrm{~T}^{0}\right]$
(b) $\left[\mathrm{ML}^{-1} \mathrm{~T}^{-2}\right]$
(c) $\left[\mathrm{ML}^{2} \mathrm{~T}^{-4}\right]$
(d) $\left[\mathrm{ML}^{2} \mathrm{~T}^{-3}\right]$