16) A body of mass 3.14 kg is suspended form one end of a wire of length 10 m. The radius if cross - section of the wire is changing uniformly from $5\times {10}^{-4} m$ at the top (i.e. point of suspension) to $9.8\times {10}^{-4} m$at the bottom. Young's modulus of elasticity is $2\times {10}^{11} N/m^2.$ The change of length of the wire is.
$$\begin{gathered} \left(a\right) 4\times {10}^{-3 } m \\ \left(b\right) 3\times {10}^{-3} m \\ \left(c\right) {10}^{-3} m \\ \left(d\right) 2\times {10}^{-3} m \end{gathered}$$