That is the way everyone should go when asked about something they don't know. There really is nothing wrong admitting you don't know something. I worked with a kid who supposedly was going to be working at our local zoo who used to tell customers he could tell the sex of our Bearded Dragons before they even came close to maturity. I loved the guy that told me that if you feed Lionfish live food they'll never take frozen food like in the wild. He honestly said that.