Which of the following includes acceptance criteria as part of its definition?

The correct answer is the user story. User stories are a key component of Agile methodologies and serve as a means to capture specific features or functionalities from the perspective of the end user. Each user story is typically accompanied by acceptance criteria, which outline the conditions that must be met for the story to be considered complete and acceptable to the stakeholders. These criteria help ensure that all requirements are clear and provide a way to validate the functionality during testing.

In contrast, while user interface and user experience are important aspects of software design, they do not inherently include acceptance criteria in their definitions. The user interface focuses on how the application looks and functions from a visual perspective, while user experience encompasses the overall satisfaction and interaction a user has with a product. The V-model, on the other hand, is a development model emphasizing planning and verification, rather than being directly linked to user stories and their criteria. Thus, user stories stand out as the correct choice due to their structured nature and emphasis on clear, testable outcomes.