You need to be specific.
Vague or general answers might not suffice. This is an opportunity for you to show that you have an understanding of the company and the job and you have an understanding of how that job fits your inclinations.
So, it goes without saying that to be able to answer this question in a proper manner you should have understand the job requirement well. One good y would be to speak to your recruiter in depth about the job role.
Basically the issue revolves around your understanding of the job details.Take some time to get into those. Perhaps try listing them out one by one and see which facet of the job really catches your eye. Develop on that – maybe enough to speak for a minute or two. Thats just about it – the interviewer will be satisfied that you have done your homework and you get a small confidence boost to handle the more tougher questions to follow.