Form Question Without Linking to Field - Please Help!

As Christiane points out, it's possible that what you want is a PMCF — that is, a program-lead field as a opposed to a global lead field.

Telling us what the form question actually is would help us help you.

While, yes, you would have to store the information in a Marketo field, you could also use Program Member Custom Fields to have a more flexible field (like "Lunch Choice" on a registration form that might change from program to program). So, if this info would be changing frequently, this could be an option for you.

You have to create it in the Field Management area, and there is a limit on these, per instance, but it gives you a bit more flexibility if your information could change from program to program.

Program Member Custom Fields 

Where do you intend to save the answer to that question, if not in a Marketo field?

I'd suggest do just take any field in Marketo - probably create one - and just use that for your question. Usually, Marketo users create one or more "flex" or "temp" fields for that exact purpose.