by Given that software is eating the world, a seasoned Scrum Master is nowadays in high demand.
Asking this question is also likely to reveal why your candidate is interested in the role of a Scrum Master in the first place.
Communicating honestly and openly is the best way for a Scrum Master to get the cooperation of a Product Owner.
A Scrum Master, in return, supports the Product Owner in building a high-value, actionable Product Backlog, and to this end must facilitate effective collaboration between the Product Owner and the Scrum Team.