To pose a question, the student wants to use one of the five Ws and How since more than one question has become unacceptable and the editors must revise the student's submission to one question. So, in considering how to pose just one question, choose the interrrogative word that will provide you with an ample response.
For instance, let's say that a student asks something like this,
How does the character ______ demonstrate ______? Why does she act this way?
Here are 2 questions that will be modified to one by an editor; most likely, the editor will just use the first one. But, if the student, instead, writes the question with WHY, the editor will probably include answers to HOW, anyway, in the process of answering the Why question. For, it is almost impossible to not describe how the character acts in order to answer why he/she acts this way.
So, word the question with just one interrogative word, but include phrasing that will lead to an editor's developing more in his/her answer.