The acceptance criteria associated with a user story are the conditions that must be met for the user story to be considered done and to deliver the expected value to the user. They are often written in different formats, such as rule-oriented, scenario-oriented, or table-oriented, depending on the nature and complexity of the user story. They represent an aspect of a user story referred to as confirmation, which is one of the so called "3 C' s" of user stories. The other two aspects are card and conversation. Card refers to the concise and informal description of the user story, usually following the template: "As a [role], I want [feature], so that I can
[benefit]". Conversation refers to the ongoing dialogue between the stakeholders and the team members to clarify and refine the user story and its acceptance criteria. Therefore, option C is the correct answer.
References: ISTQB Certified Tester Foundation Level Syllabus v4.01, Section 3.2.2, page 35-36; ISTQB Glossary v4.02, page 37.