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