On the surface, this appears to be a simple question, yet it is easy to slip. I would suggest not mentioning money at this stage as you may come across as totally mercenary. If you are currently employed, you can say it's about developing your career and yourself as an individual. If you are in the unfortunate position of having been downsized, stay positive and keep it brief. If you were fired, you should have a solid explanation. Whatever your circumstances, do not talk about the drama but remember to stay positive.