You said you have a few gaps right? How long ago was the latest one?

Aside from stating that you were being a care-giver and looking after someone (you don't even have to say it's a family member), you could also just point out that the job-market has been rather horrible for a while now and that you have been amongst many people who have had trouble looking. There you're providing an answer as to what you were doing, (which is obviously something you WERE just doing if you just had an interview) although it does dodge the reason why you stopped work.

Depending on what sort of place you've worked at, you could say lay-offs.