Which of the following is optically active :-

• A

  $\begin{array}{*{20}{c}}
    {C{H_3} - {\mkern 1mu} {\mkern 1mu} CH - COOH} \\ 
    {|\,\,\,\,\,\,\,\,\,\,\,} \\ 
    {{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} OH\,\,\,\,\,\,\,\,\,\,} 
  \end{array}$

• B

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

• C
  
• D

  None