55. What will be the output of the following code?
   
    public class Test
    {
      public static void main( String []args ) {
      StringBuffer a = new StringBuffer("A");
      StringBuffer b = new StringBuffer("B");
      operate( a,b );
      System.out.println( a + "," + b );
      }
         
      public static void operate( StringBuffer x, StringBuffer y ) {
      x.append( y );
      y = x;
      }
    }
         
   Select 1 correct answer:
A. A, B
B. The code will not compile.
C. B, A
D. AB, B