[Pt(Cl)2(NH3)2] forms two possible geometrical isomers, cis and trans.
In cis, same group on same side and in trans same groups on opposite side.
In
[Ni(CO)4], the oxidation state of Ni is 0 and it forms a outer orbital complex with
sp3 hybridisation. Thus, it form tetrahedral complex and it lacks geometrical isomerism.
In
[Ma3b3] type of complex, the possible geometrical isomers are two, facial and meridional.
Facial isomer have three identical ligands on one triangular face.
Meridional isomer have three identical ligands in a plane bisecting the molecule.
In
[Ma2b4] type, there are two possible geomerical isomers, cis and trans.
These isomers are given below,
Hence, option (c) is correct.