The graph shown the extension of wire of length 1 m suspended from the top of a roof at one end and with a load W connected to the other end. If the cross sectional area of the wire is 1 mm² , then the Young's modulus of the material of the wire is 
 

• A

  $2\times {10}^{11}{\mathrm{Nm}}^{-2}$

• B

  $2\times {10}^{10} {\mathrm{Nm}}^{-2}$

• C

  $\frac{1}{2}\times {10}^{11}{\mathrm{Nm}}^{-2}$

• D

  none of these