|In a job interview, the questions that an applicant asks are as important as the questions you ask. You can gain a great deal of insight into applicants from their questions, as well as from their lack of questions.|
Obviously you did not like the question she asked you, but she has a perfect right to ask it, and she may have raised an important issue. You indicated that you think your inquires were all legal, but that is different from saying you are one hundred percent certain your questions are legal. You are upset about her question, and you are probably somewhat upset that you could not give an unequivocal answer. This is a good time to take a second look at all of your pre-employment inquiries and make sure that they are job related or work samples or simulations.
At the same time, there can be inappropriate questions from an applicant, such as those that are overly personal, hostile, or bizarre. You should judge all questions on a businesslike and professional basis, and use them as a source of additional data about the applicant and, in some cases, about your company.