Nickel (Z=28) combines with a uninegative monodentate ligand to form a diamagnetic complex $\;[NiL_{4}]^{2-}\;$ . The hybridisation involved and the number of unpaired electrons present in the complex are respectively :

Question

$(a)\;sp^{3}\;,two \qquad(b)\;dsp^{2}\;,zero \qquad(c)\;dsp^{2}\;,one \qquad(d)\;sp^{3}\;,zero $