The definition of done (DoD) is a checklist of all the criteria required to be met so that a deliverable can be considered ready for customer use. In an agile context, the decision of when an MVP meets the DoD and can be released to the customer is typically made by the agile team. The team works together to ensure that the MVP meets the DoD and is ready for release to the customer. This decision is based on the team's assessment of whether the MVP meets the acceptance criteria and is of sufficient quality to be released. This helps to prevent misunderstandings and ensures that everyone is working towards the same goal.
The other options are incorrect.
The scrum master determining that all requirements are satisfied is important, but the decision is ultimately based on the assessment of the entire team.
The senior manager and customer approving and accepting the product is not a direct indicator of whether the product is ready for customer use.
The product owner's agreement that the MVP passed quality testing is important, but quality testing is only one part of a broader range of criteria and the entire project team should be involved.