How to indicate a parent child category relationship when bulk importing

I have a custom post of Business and each Business has a primary category(parent) and secondary category(child) with taxonomy fields using Advanced Custom Fields. I’m going to be importing into a fresh install that doesn’t have any categories set yet and I’m importing from a spreadsheet. So my question is how do I identify or create the parent/child relationship? My spreadsheet has a column for the primary category(parent) and one for the secondary category(child). But how do I indicate that the secondary category is a child of the primary category(parent)?