Square-planar geometry is shown by

When an aqueous solution of copper $(II)$ sulphate is saturated with ammonia,the blue compound crystallises on evaporation. The formula of this blue compound is

What is the geometry of the $[Ni(CO)_4]$ complex?

Given below are two statements :
Statement $I$: $[Ni(CN)_4]^{2-}$ is square planar and diamagnetic complex with $dsp^2$ hybridization for $Ni$ but $[Ni(CO)_4]$ is tetrahedral,diamagnetic and with $sp^3$ hybridization for $Ni$.
Statement $II$: $[NiCl_4]^{2-}$ and $[Ni(CO)_4]$ both have same $d$-electron configuration,have same geometry and are paramagnetic.
In light of the above statements,choose the correct answer from the options given below:

Which of the following sequences of hybridisation, geometry, and magnetic nature are correct for the given coordination compounds?
$A.$ $[NiCl_4]^{2-}$ – $sp^3$, tetrahedral, paramagnetic  
$B.$ $[Ni(NH_3)_6]^{2+}$ – $sp^3d^2$, octahedral, paramagnetic  
$C.$ $[Ni(CO)_4]$ – $sp^3$, tetrahedral, paramagnetic  
$D.$ $[Ni(CN)_4]^{2-}$ – $dsp^2$, square planar, diamagnetic  
Choose the correct answer from the options given below:

The number of unpaired electrons in $[NiCl_{4}]^{2-}$, $Ni(CO)_{4}$ and $[Cu(NH_{3})_{4}]^{2+}$ respectively are