A wire having area of cross section ${10}^{-6}{\mathrm{m}}^2$ is stretched to increase its length by 0.1%. Then tension produced is 1000N. Then elastic potential energy stored per unit volume of the wire is 

• A

  $5\times {10}^5\mathrm{J}/{\mathrm{m}}^3$

• B

  ${10}^8\mathrm{J}/{\mathrm{m}}^3$

• C

  $2\times {10}^6\mathrm{J}/{\mathrm{m}}^3$

• D

  $5\times {10}^6\mathrm{J}/{\mathrm{m}}^3$