Never respond with negativity! Ever. Period. It only signals red flags. Whenever you answer this question, respond positively. Do not appear like you are running away from something bad; appear like you are running toward something great. For instance, you could say that although you LOVE what you do and where you work, moving into this new role will be an opportunity to advance or broaden your skill sets. OR you can mention that you have heard great things about this new role and thought that you would be doing a disservice to yourself and your career path if you didn’t at least pursue the good opportunity.