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.