Correct Answer - C
`Cu^(2+)+"excess"CN^(-)to underset("colourless sol")([Cu(CN)_4]^(3-))`
`Cu^(+) , 3d^(10) implies sp^3` , diamagnetic & tetrahedral
`Zn^(2+)+"excess"NH_3(aq)tounderset("Colourless solution")([Zn(NH_3)_4]^(2+))`
`Zn^(2+), 3d^10 implies sp^3` tetrahedral diamagnetic