Definition
A buyer question is a complete, natural question a real buyer would type into an assistant, such as which option suits a stated situation. It is the unit of measurement in GEO, and it is not a keyword: keywords are fragments, buyer questions are sentences with a situation in them.
Why it matters
Assistants answer situations, not fragments. A question that carries a budget, a constraint or a use case produces a different set of named brands than the bare category term does.
How to measure it
Keep a fixed set across runs so results are comparable, and record intent for each question so you can see whether you are absent everywhere or only at the purchase end.