Option C is the best approach as it directly addresses the need for customer segmentation based on purchase behavior, a key requirement for targeted marketing campaigns. By using clustering algorithms within Microsoft Fabric Analytics, the analysis is scalable and can handle large datasets efficiently. Additionally, anonymizing personal data before analysis ensures compliance with data privacy regulations. While options A, B, and D provide valuable insights, they either do not focus on customer segmentation or fail to fully leverage the capabilities of Microsoft Fabric Analytics in a scalable and privacy-compliant manner.