It's actually 2 questions in one, but it will most times reveal the seriousness of your prospect and his/her reasons "why" for pursuing a business.
"How long have you been looking for a business form home?"
"What happened XX time ago that started you searching?"
Question one tells you if they just hopped on last night and are tire kicking; or if they have been on the serious hunt for awhile.
Question two will tell you the reason why. Sometimes it's a new mother who just went back to work and cried all day after leaving her child at daycare.
Sometimes it's the tenth time the prospect was passed over for a promotion. Maybe an aging parent who needs assistance.
Lots of reasons "why" out there.
Listen closely and then you can present your opportunity in such a way that shows him/her how your business is a fit for the reason "Why!"