Which of the following complexes can exhibit facial $(fac)$ and meridional $(mer)$ isomerism?

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

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

Calculate the magnetic moment of the $Fe^{3+}$ ion in the $[Fe(CN)_6]^{3-}$ complex.

Given below are two statements:
Statement $I$: Both $[Co(NH_3)_6]^{3+}$ and $[CoF_6]^{3-}$ complexes are octahedral but differ in their magnetic behaviour.
Statement $II$: $[Co(NH_3)_6]^{3+}$ is diamagnetic whereas $[CoF_6]^{3-}$ is paramagnetic.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following exhibits optical isomerism?