According to the Scrum Guide, the Product Owner must participate in the Daily Scrum when he or she is actively working on items on the Sprint Backlog; however, they participate as a Developer, not as an authority figure. This means that the Product Owner can share progress, plans, and impediments with the other Developers and collaborate with them on delivering value. The other options are not valid reasons for the Product Owner to participate in the Daily Scrum, as they are either irrelevant (such as representing stakeholders or discussing impediments) or inappropriate (such as being asked by the Scrum Master).