Which of the following is optically active

• A
  
• B

  $\begin{array}{*{20}{c}}
    {C{H_3} - CH - C{H_2}} \\ 
    {\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,} \\ 
    {\,\,\,\,\,\,\,\,\,Cl\,\,\,\,\,\,\,\,\,\,\,Cl} 
  \end{array}$

• C

  $\begin{array}{*{20}{c}}
    {\begin{array}{*{20}{c}}
    {\begin{array}{*{20}{c}}
    {Cl} \\ 
    | 
  \end{array}} \\ 
    {C{H_3} - C - C{H_3}} 
  \end{array}} \\ 
    | \\ 
    {Cl} 
  \end{array}$

• D

  $\begin{array}{*{20}{c}}
    {{H_2}C - C{H_2} - C{H_2}} \\ 
    {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
    {\,\,Cl\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Cl} 
  \end{array}$