In which of the following pairs both the complex's show optical isomerism?

3+ and cis-[Co(en)2Cl2]+]$[\text{Co}(\text{en}{)}_3{]}^{3+}$ is a chelating octahedral complex of type $M(aa{)}_3$ which exists as a pair of enantiomers ($d$ and $l$ forms).$cis$ -$[\text{Co}(\text{en}{)}_2{\text{Cl}}_2{]}^{+}$ is a chiral complex because it lacks a plane of symmetry, unlike the $trans$ isomer.Both complexes in pair (b) show optical isomerism.