Which one of the following octahedral complexes will not show...

Geometric isomerism occurs in octahedral complexes when there are at least two different types of ligands or when there is a bidentate ligand present. Geometric isomerism is not possible when all ligands are the same type and are monodentate. In such cases, the ligands can only occupy adjacent positions in the octahedral coordination sphere. Among the options given: (1) (\left[M A_2 B_4\right]) has two types$of ligands ($A$and$B), so it can exhibit geometric isomerism. (2) (\left[M A_3 B_3\right]) has two types$of ligands ($A$and$B), so it can exhibit geometric isomerism. (3) (\left[M_4 B_2\right]) has two types$of ligands ($A$and$B), so it can exhibit geometric isomerism. (4) (\left[\mathrm{MA}_{5}\mathrm{~B}\right] has only one type of ligand ($A$), and they are all monodentate. Therefore, it will not show geometric isomerism.