Your interviewer asks this question to assess whether you can fulfill new responsibilities at their organization and whether you fit well with their culture. When putting your response together, align the responsibilities and opportunities at your current role with the one you're applying for. Assure your interviewer that you've done your research on the job and the culture by speaking about what makes you excited for the new job. No matter how you answer this question, be sure to speak with passion as that will be one of the top qualities they will be looking for in the candidate that they hire.