Any way to simplify this Drill Down question?

Hello,
I have a survey question I'm trying to program as a Drill Down, but I'm not sure how feasible it is or if I'm overthinking it. I have 3 questions, each one dependent on the Q before. The first is to choose from a list of 31 focus areas --> then choose from a list of 20 activities within that focus area --> then choose from a list of 19 priority populations those activities are serving.
The way I understand Drill Down questions is that I would need to make a row for every possible answer - which would be close to 12,000 rows. I don't have the capacity to do that - so I'm wondering if there's a simpler way I'm not thinking of?
Thanks in advance!