Four test tubes A, B, C and D are taken. In test tube A iron nail is dipped in copper sulphate solution. In test tube B copper wire is dipped in ferrous sulphate solution. In test tube C zinc metal is dipped in ferrous sulphate solution and in test tube D iron nail is dipped in zinc sulphate solution. The reactivity order has been found to be `Zn gt Fe gt Cu`. In which test tubes was the colour change observed ?

Options

A. A and C
B. A and B
C. B and C
D. B and D