'A' is a steel rod of length I_A and 'B' a copper rod of length l_B. Values of l_A and l_B such that l_A -l_B = 5 cm at all temperatures, are :
(Given ${\mathrm{\alpha }}_{\mathrm{Cu}}=1.7\times {10}^{-5}/{}^{\mathrm{o}}\mathrm{C},{\mathrm{\alpha }}_{\mathrm{st}eel}=1.1\times {10}^{-5}/{}^{\mathrm{o}}\mathrm{C}$)

• A

  21.4 cm, 16.4 cm

• B

  10.8 cm, 5.8 cm

• C

  14.2 cm, 9.2 cm

• D

  32.4 cm, 27.4 cm