The correct order of the calculated spin only magnetic moments of complexes (A) to (D) is:
 (A) Ni(CO)₄
(B) [Ni(H₂O)₆]Cl₂
(C) Na₂[Ni(CN)₄]
(D) PdCl₂(PPh₃)₂

$$\begin{gathered} {\mathrm{Na}}_2\left[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4\right] \\ {\mathrm{Ni}}^{2+ }= 3{\mathrm{d}}^8 (\mathrm{it} \mathrm{has} \mathrm{strong} \mathrm{field} \mathrm{ligand})\mathrm{Number} \mathrm{of} \mathrm{unpaired} {\mathrm{e}}^{-} = 0 \\ \mathrm{\mu } = 0 \mathrm{B}. \mathrm{M} \\ {\mathrm{PdCl}}_2{(\mathrm{P} \mathrm{P} {\mathrm{h}}_3)}_2 {\mathrm{Pd}}^{2+ }= 4{\mathrm{d}}^8( \mathrm{it} \mathrm{is} \mathrm{dimagnetic}),\mathrm{\mu } = 0 \mathrm{B}.\mathrm{M} \end{gathered}$$

Hence correct option is (A),(A) = (C) =  (D) < (B)