Correct Answer - A
`[Ni(CN)_4 ]^(2 -)`
Let oxidation state of Ni in `[Ni(CN)_4 ]^(2 -)` is x
`therefore x-4 = -2`
or x= 2
Now, `Ni^(2+) = [Ar] 3d^8 4s^0`
`therefore CN^-`is a strong field ligand. Hence, all unpaired electrons are paired up.
`therefore " Hybridisation of " [Ni(CN)_4 ]^(2 -) is dsp^(2)`