The complex which doesn’t exhibit geometrical isomerism is 

• A

  ${\mathrm{Ma}}_3{\mathrm{b}}_3$

• B

  $\mathrm{M}{\left(\mathrm{aa}\right)}_2{\mathrm{b}}_2$

• C

  $\mathrm{square}\mathrm{planar}{\mathrm{Ma}}_2{\mathrm{b}}_2$

• D

  $\mathrm{tetrahedral}\mathrm{MabXL}$