Correct Answer: DArticle 5(1)(b) of the GDPR specifically addresses the principle of purpose limitation, meaning that personal data should only be collected for specified, explicit, and legitimate purposes and not further processed in a manner that is incompatible with those purposes. The interpretation of the term 'incompatible' by a member state would indeed indicate the degree of flexibility a controller has in using personal data in ways that may vary from its original intended purpose. Thus, it determines how strictly controllers must adhere to the original purpose for which the data was collected, making option D the most accurate.