<img src="https://nimg.ppkao.com/2018-07/luke/2018073111541118948.jpg?sign=0c85067af7df5ff38ca03edf16dd9446&t=62d41948" /><br /> What code, inserted at line 21, is called prior to a session being migrated to a different JVM assuming the web application containing MyExample is deployed in a container which supports distributed applications?()
A、 public void valueUnbound(HttpSessionEvent ev){...}
B、 public void sessionPassivated(HttpSessionEvent ev){...}
C、 public void sessionDidActivate(HttpSessionEvent ev){...}
D、 public void sessionWillPassivate(HttpSessionEvent ev){...}