问题：

[单选]

public class X implements Runnable（  
 private int x；  
private int y； 
 public static void main（Stringargs） 
X that = new X（）；  
（new Thread（that））.start（）； 
（new Thread（that））.start（）； 
） 
public void run（） （ 
for （；；） （ 
x++；  
y++；  
System.out.printIn（“x=” + x + “， y = ” + y）；  
）  
）  
What is the result？（）  

A .  Errors at lines 7 and 8 cause compilation to fail.
B .  The program prints pairs of values for x and y that might not always be the same on the same line  （for example， “x=2， y=1”）.
C .  The program prints pairs of values for x and y that are always the same on the same line （for example， “x=1， y=1”. In addition， each value appears twice （for example， “x=1， y=1” followed by  “x=1， y=1”）.
D .  The program prints pairs of values for x and y that are always the same on the same line （for example， “x=1， y=1”. In addition， each value appears only for once （for example， “x=1， y=1”  followed by “x=2， y=2”）.