A rod of length 40 cm has the coefficient of linear expansion ${\mathrm{\alpha }}_1=6\times {10}^{-6}/{}^{\mathrm{o}}\mathrm{C}$. The other rod has coefficient of linear expansion, ${\mathrm{\alpha }}_2=4\times {10}^{-6}/{}^{\mathrm{o}}\mathrm{C}$. If the difference in their lengths at all temperatures remains the same, the length of the other rod is:

• A

  26 cm

• B

  32 cm

• C

  60 cm

• D

  80 cm