Which of the following complexes is diamagnetic and tetrahedral?

Magnetic moment (spin only) of an octahedral complex having $CFSE = -0.8 \Delta_0$ and surrounded by weak field ligands can be

Give the oxidation state,$d$-orbital occupation,and coordination number of the central metal ion in the following complexes:
$(i)$ $K_{3}[Co(C_{2}O_{4})_{3}]$
$(ii)$ $cis-[Cr(en)_{2}Cl_{2}]Cl$
$(iii)$ $(NH_{4})_{2}[CoF_{4}]$
$(iv)$ $[Mn(H_{2}O)_{6}]SO_{4}$

Given below are two statements:
Statement $I$ : Dimethyl glyoxime forms a six-membered covalent chelate when treated with $NiCl_2$ solution in presence of $NH_4OH$.
Statement $II$ : Prussian blue precipitate contains iron both in $(+2)$ and $(+3)$ oxidation states.
In the light of the above statements,choose the most appropriate answer from the options given below:

The coordination number of $Ni^{2+}$ is $4$.
$NiCl_2 + KCN$ (excess) $\rightarrow A$ (cyano complex)
$NiCl_2 + \text{Conc. } HCl$ (excess) $\rightarrow B$ (chloro complex)
$1.$ The $IUPAC$ names of $A$ and $B$ are:
$(A)$ Potassium tetracyanonickelate $(II)$,potassium tetrachloronickelate $(II)$
$(B)$ Tetracyanopotassiumnickelate $(II)$,tetrachloropotassiumnickelate $(II)$
$(C)$ Tetracyanonickel $(II)$,tetrachloronickel $(II)$
$(D)$ Potassium tetracyanonickel $(II)$,potassium tetrachloronickel $(II)$
$2.$ Predict the magnetic nature of $A$ and $B$:
$(A)$ Both are diamagnetic.
$(B)$ $A$ is diamagnetic and $B$ is paramagnetic with one unpaired electron.
$(C)$ $A$ is diamagnetic and $B$ is paramagnetic with two unpaired electrons.
$(D)$ Both are paramagnetic.
$3.$ The hybridization of $A$ and $B$ are:
$(A)$ $dsp^2, sp^3$
$(B)$ $sp^3, sp^3$
$(C)$ $dsp^2, dsp^2$
$(D)$ $sp^3 d^2, d^2 sp^3$
Give the answers for questions $1, 2$ and $3$.

Which of the following statements is correct?