public class SyncTest {  private int x；  private int y；  public synchronized void setX （int i） （x=1；）  public synchronized void setY （int i） （y=1；）  public synchronized 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.