问题：

[单选]

public class SyncTest （  
private int x；  
private int y；  
private synchronized void setX （int i） （x=1；）  
private synchronized void setY （int i） （y=1；）  
public void setXY（int 1）（set X（i）； setY（i）；）  
public synchronized Boolean check（） （return x !=y；）  
 ）  
Under which conditions will check （） return true when called from a different class？

A .  Check（） can never return true.  
B .  Check（） can return true when setXY is called by multiple threads.  
C .  Check（） can return true when multiple threads call setX and setY separately.  
D .  Check（） can only return true if SyncTest is changed to allow x and y to be set separately.