Allison, a Certified Fraud Examiner (CFE).

The manual defines:

“Open questions are those worded in a way that makes it difficult for the respondent to answer ‘yes’ or ‘no.’ The typical open question calls for a monologue response and can be answered in several different ways.”

Example given: “Please tell me about your job.”

Allison’s question (“Why did you choose to do business with that vendor?”) invites explanation, not a yes/no response — making it an open question.