An aluminum wire and a copper wire of the same length and cross section are joined end to end. The composite wire is hung from a rigid support and a load is suspended from the free end. if the increase in length of the composite wire is 1.8mm, find the increase in the length of each wire. $({\text{Y}}_{\text{Al}}=\text{7}\times \text{1}{0}^{\text{1}0}{\text{Nm}}^{–\text{2}},{\text{ Y}}_{\text{Cu}}=\text{1}.\text{1}\times \text{1}{0}^{\text{11}}{\text{Nm}}^{–\text{2}})$

• A

  1.1 mm,  0.7 mm

• B

  0.7 mm,  1.1 mm

• C

  2.2 mm,  1.4 mm

• D

  1.4 mm,  2.2 mm