Scrum Definition of Done

The main responsibility of a Scrum Master is to ensure that the scrum team adheres to Scrum theory, practices, and rules. Each increment must be 'potentially shippable', meaning integrated into the existing software and tested. Although it might not be explicitly mentioned in the team's Definition of Done, it is a fundamental requirement of Scrum and Agile development. Hence, the Scrum Master should remind the team of this. The other options are incorrect because: throwing a formal complaint does not foster a supportive and collaborative environment, approving the increment disregards the principles of Scrum, asking the Product Owner to decide is not his/her responsibility, as the Product Owner is more focused on maximizing value, not deciding on technical aspects of the product.

Scrum is an iterative process that focuses on delivering functional bits of application at each iteration. The key to these quick iterations is maintaining a good-quality product. This is achieved by setting a clear Definition of Done. In Scrum, the Definition of Done helps the team understand what needs to be finished before a product backlog item can be called 'done.' If the team is confused about including unit tests in this definition, the ScrumMaster should encourage them to include it as it ensures that all individual parts of code are correctly working. This is crucial to maintaining the deliverable's functionality and quality. The other answers are not best practices in Scrum. Excluding unit tests can lead to a reduction in product quality, a simple vote doesn't guarantee the right decision will be made, quality cannot be compromised. Including a unit test only for critical parts of the code goes against the spirit of comprehensive testing, as it may lead to overlooking other potentially problematic areas.

The Definition of Done is created during the Sprint Planning Meeting. This is the time when the Scrum team plans and determines the work and tasks that need to be accomplished in the upcoming Sprint. They also set the required criteria or 'Definition of Done' that must be met for the work to be considered complete. It is not created in the Sprint Review Meeting since this meeting is held at the end of the sprint to review the completed work and adapt product backlog if needed. The Daily Scrum Meeting is mainly for monitoring the progress of the sprint and dealing with any emergent issues, not for specifying the Definition of Done. As for the Retrospective Meeting, it is a reflection activity performed after the sprint to improve the team's processes and performance for the upcoming sprints; hence it is not when the Definition of Done is formed.