The hybridised orbitals used by silver in the complex $[Ag(NH_3)_2]^+$ are of the type

$[Cu(NH_3)_4]^{2+}$ shows the following hybridization:

The shape of $[Cu(NH_3)_4]^{2+}$ is square planar. The $Cu^{2+}$ ion in this complex is:

The geometry and magnetic behaviour of the complex $[Ni(CO)_4]$ are

The pair$(s)$ of complexes wherein both exhibit tetrahedral geometry is(are):
Note: $py = \text{pyridine}$
Given: Atomic numbers of $Fe, Co, Ni$ and $Cu$ are $26, 27, 28$ and $29$,respectively.
$(A)$ $[FeCl_4]^-$ and $[Fe(CO)_4]^{2-}$
$(B)$ $[Co(CO)_4]^-$ and $[CoCl_4]^{2-}$
$(C)$ $[Ni(CO)_4]$ and $[Ni(CN)_4]^{2-}$
$(D)$ $[Cu(py)_4]^+$ and $[Cu(CN)_4]^{3-}$

The species having tetrahedral shape is