Which principle of Agile methodology does this violate?

The user acceptance testing (UAT) of a solution has passed. During the code review process, a technical team found that the Apex code fails to meet Salesforce coding standards which makes it challenging to maintain over the long term and may create performance issues. The business analyst has identified this as an issue that prevents deployment to production.

Which principle of Agile methodology does this violate?
A . Sprint retrospective
B. Definition of done
C. Iterative development

Answer: B