Q1: What will be the output of the program?

class Test116 
{ 
static final StringBuffer sb1 = new StringBuffer(); 
static final StringBuffer sb2 = new StringBuffer(); 
public static void main(String args[]) 
{ 
    new Thread() 
    { 
        public void run() 
        { 
            synchronized(sb1) 
            { 
                sb1.append('A'); 
                sb2.append('B'); 
            } 
        } 
    }.start(); 

    new Thread() 
    { 
        public void run() 
        { 
            synchronized(sb1) 
            { 
                sb1.append('C'); 
                sb2.append('D'); 
            } 
        } 
    }.start(); /* Line 28 */

    System.out.println (sb1 + ' ' + sb2); 
    } 
}