The best answer is C. When multiple Scrum Teams are working on a single product, they must mutually define and comply with the same Definition of Done1. This ensures that the product has a consistent level of quality and that the Increments delivered by different teams can be integrated seamlessly. Having different Definitions of Done for each team can lead to confusion, rework, and technical debt. The Scrum Guide says that the Definition of Done is a formal description of the state of the Increment when it meets the quality measures required for the product2. Therefore, it is not something that can be decided by the Scrum Masters alone (B) or left to each team's discretion (A and D).