Which of the following complexes will not show optical isomerism?

Select the complex in which the metal has primary valency $= 2$,secondary valency $= 4$ and shows stereo-isomerism:

Which one of the following does not exhibit geometrical isomerism?

What kind of isomerism exists between $[Cr(H_2O)_6]Cl_3$ and $[Cr(H_2O)_5Cl]Cl_2 \cdot H_2O$?

What is the ionization isomer of $[Cr(H_2O)_4Cl(NO_2)]Cl$?

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ The spin only magnetic moment value for $[Fe(CN)_6]^{3-}$ is $1.74 \ BM$,whereas for $[Fe(H_2O)_6]^{3+}$ is $5.92 \ BM$.
Reason $R:$ In both complexes,$Fe$ is present in $+3$ oxidation state.
In the light of the above statements,choose the correct answer from the options given below: