Which of the following complexes exhibits both geometric and optical isomerism?

The pair in which both species have the same magnetic moment (spin-only value) is:

In $Cr^{2+}, Mn^{2+}, Fe^{2+},$ and $Ni^{2+}$,the number of electrons in the $3d$ orbital are $3d^4, 3d^5, 3d^6,$ and $3d^8$ respectively. Which of the following aqueous complexes will have the lowest magnetic moment?

The isomerism exhibited by $[Co(NH_3)_5(SO_4)]Br$ and $[Co(NH_3)_5(SO_4)]Cl$ is of the ........ type.

The number of possible optical isomers for the complexes $MA_{2}B_{2}$ with $sp^{3}$ and $dsp^{2}$ hybridised metal atom,respectively,is.
Note : $A$ and $B$ are unidentate neutral and unidentate monoanionic ligands,respectively.

Given below are two statements:
Statement $I$: $A$ homoleptic octahedral complex,formed using monodentate ligands,will not show stereoisomerism.
Statement $II$: $cis-$ and $trans-$ platin are heteroleptic complexes of $Pd$.
In the light of the above statements,choose the correct answer from the options given below.