User acceptance testing is a process of verifying that the product meets the user’s needs and expectations. It is an important feedback mechanism that helps the Scrum Team validate their assumptions, inspect the value and quality of the Increment, and adapt their plans accordingly. Scrum requires that the Increment be transparent, meaning that it is observable and understandable by anyone with a stake in the outcome. Scrum also requires that the feedback loop be short, meaning that the Scrum Team can receive and respond to feedback quickly and frequently.

Therefore, it is not a good idea to have user acceptance testing done every third Sprint, because:

The Increment will not be transparent (B), meaning that the Scrum Team and the stakeholders will not have a clear and shared understanding of what has been done and what remains to be done. This may lead to misalignment, confusion, or conflict over the product vision, scope, and quality.

The feedback loop is too long (B), meaning that the Scrum Team will not be able to inspect and adapt based on the user’s feedback in a timely manner. This may lead to wasted effort, missed opportunities, or reduced value delivery.

The other options are not correct because:

It does not depend on what is stated in their Definition of Done (A), which is a formal description of the state of the Increment when it meets the quality standards required for the product. The Definition of Done does not dictate how or when user acceptance testing should be done, but rather what criteria must be met for the Increment to be considered “Done”.

The Scrum Team is a self-managing team ©, which means that they have the autonomy and authority to organize and manage their own work within theboundaries of Scrum. However, this does not mean that they can ignore or postpone user feedback, which is essential for delivering value and satisfying customer needs.

The Scrum Team needs stability in the Sprint (D), which means that they need to have a clear and consistent Sprint Goal, Sprint Backlog, and Definition of Done throughout the Sprint. However, this does not mean that they need to avoid or resist user feedback, which is a source of learning and improvement for the product and the process.

References: : [Scrum Guide], The Increment : [Scrum Guide], Transparency : [Scrum Guide], The Definition of Done : [Scrum Guide], The Scrum Team : [Scrum Guide], The Sprint Goal