Which method can enhance customer data by relational data tables in Marketing Cloud?

Enhancing customer data by relational data tables in Marketing Cloud primarily involves using Contact Builder integration. This tool allows users to centralize and manage customer data across various sources and create a unified view of customers by linking multiple data extensions together through relationships.

Through Contact Builder, marketers can define how different data tables interact with each other, enabling the integration of relational data. This integration facilitates personalized customer interactions based on comprehensive data insights, enhancing the overall marketing effectiveness.

The other methods, while valuable for managing data, do not offer the same level of relational data integration. Importing data from a customer's data warehouse can create new records but does not inherently enhance data through relationships. Engagement Studio focuses on orchestrating marketing campaigns and customer journeys rather than enhancing data. Modifying data extensions may be necessary for managing data, but it does not provide the relational capabilities that Contact Builder does.