Consider the complex ions,$trans-[Co(en)_2Cl_2]^+$ $(A)$ and $cis-[Co(en)_2Cl_2]^+$ $(B)$. The correct statement regarding them is :

• A
  both $(A)$ and $(B)$ can be optically active
• B
  both $(A)$ and $(B)$ cannot be optically active
• C
  $(A)$ can be optically active,but $(B)$ cannot be optically active
• D
  $(A)$ cannot be optically active,but $(B)$ can be optically active