$CH_3 - CHCl - CH_2 - CH_3$ has a chiral centre. Which one of the following represents its $R-$configuration ?

• A

  $\begin{array}{*{20}{c}}
    {{C_2}{H_5}} \\ 
    | \\ 
    {H - C - C{H_3}} \\ 
    | \\ 
    {Cl} 
  \end{array}$

• B

  $\begin{array}{*{20}{c}}
    {{C_2}{H_5}} \\ 
    | \\ 
    {Cl - C - C{H_3}} \\ 
    | \\ 
    H 
  \end{array}$

• C

  $\begin{array}{*{20}{c}}
    {C{H_3}} \\ 
    | \\ 
    {H - C - C{H_3}} \\ 
    | \\ 
    {{C_2}{H_5}} 
  \end{array}$

• D

  $\begin{array}{*{20}{c}}
    {\,\,\,\,\,\,\,{C_2}{H_5}} \\ 
    {\,\,\,\,|} \\ 
    {{H_3}C - C - Cl} \\ 
    {\,\,\,\,|} \\ 
    {\,\,\,\,\,\,H} 
  \end{array}$