Which one of the following complexes shows optical isomerism ?

Question

$\begin{array}{1 1} (1) [Co(NH_3)_3Cl_3] \\ (2) cis[Co(en)_2Cl_2]Cl \\ (3) trans [Co(en)_2Cl_2]Cl\\ (4) [Co(NH_3)_4Cl_2]Cl \end{array} $