现有：  class Tree {  private static String tree = "tree "；  String getTree （）  {  return tree；  }       }  class Elm extends Tree {  private static String tree = "elm "；  public static void main （String  []  args）  {       new Elm（） .go （new Tree（））  ；      } }  void go （Tree t）  {  String  s =  t.getTree （） +Elm.tree  +  tree  +   （new  Elm（） .getTree （）） ；      System.out.println （s） ；}     结果为：（）                 

• A、 elm elm elm elm
• B、 tree elm elm elm
• C、 tree elm elm tree
• D、 tree elm tree elm