Every Scrum Team must have a Product Owner and Scrum Master.

According to the Scrum Guide, every Scrum Team must have a Product Owner and a Scrum Master, as they are essential roles for Scrum. The outcomes of the Scrum Team are affected by their participation and availability, as they provide guidance, support, and facilitation to the Development Team and the stakeholders. The other options are false, as they imply that a Product Owner or a Scrum Master can be replaced or optional, which is not consistent with Scrum.