Seems like a trick question but I would have to say they all do. This is because all are passed an EventObject (subclass) that has reference to the associated HttpSession object. Through HttpSession.getContext(), the above listeners can call the associated parameter methods to retrieve the names and values of the context parameters.
Joined: Feb 17, 2008
but the answer given as b & c. Dont know why a & d are wrong.
Joined: Jun 14, 2008
So it was a trick question.
Your failure to provide that information up front is likely the reason why your question went unanswered for as long as it did. Your failure to provide information on where the question came from leaves little else to go on. The idea here is to make it as easy as possible for others to answer your question. If you also include where the question is from maybe someone else has come across it and has the answer, or knows that the provided answer is in fact wrong (because they reviewed the errata).
However, in this case (assuming they are listed in A-D alphabetical order), I have not identified why A and D would be wrong. Extensive analysis was not performed because it does not appear to be necessary.