Complexes with $CN^-$ ligands are generally...

Which one of the following statements is correct for $d^4$ ions $(P = \text{pairing energy})$?

What is the correct order of increasing field strength for the ligands $NH_3$,$en$,$CN^-$,and $CO$?

The configurations of the complexes of manganese $A$ and $B$ respectively are $t_{2g}^3 e_g^1$ and $t_{2g}^4 e_g^0$. Then $A$ and $B$ are:

According to crystal field theory,the $M-L$ bond in a complex is

Why are different colours observed in octahedral and tetrahedral complexes for the same metal and same ligands?