A metal tape is calibrated at ${20}^{0}C. \alpha$ of metal is $2\times {10}^{-5}{/}^0\mathrm{C}.$ Distance between 2 points is measured as 1 m at ${30}^{\circ }\mathrm{C}$. Correction to be made to get true distance is 
 

• A

  $2\times {10}^{-4}\mathrm{m}\text{ is to be deducted }$

• B

  $2\times {10}^{-4}\mathrm{m}\text{ is to be added }$

• C

  $4\times {10}^{-4}\mathrm{m}\text{ is to be deducted }$

• D

  $4\times {10}^{-4}\mathrm{m}\text{ is to be added }$