Edit
This is greatly complicated by the fact that the questions don't even have their own tags. So you're in the awkward spot of needing to hide a question's parent tag, but show the question itself, which is basically impossible.
To get around this problem, here is a hack I put together. It clones the questions and appends them in their own tag. But, I'd recommend trying to prevail on the authors of this markup to revise it into something more rational.
To hide the non-questions, it looks like you could use something like:
$("#container").children().not($("strong").parent()).not("p").hide();
To show an answer, you could probably use nextUntil
:
$(this).parent().nextUntil($("strong").parent()).show();