public class SyncTest {  private int x；  private int y；  private synchronized void setX（ int i ） { x = i； }  private synchronized void setY（ int i ） { y = i； }  public void setXY（ int i ） { setX（i）； setY（i）； }  public synchronized boolean check（） { return x != y； }  }   Under which condition 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 return true only if SyncTest is changed to allow x and y to be set separately.