b) Using a Salesforce record ID as a single unique identifier to apply across channels and clouds can help ensure GDPR compliance by enabling data portability, deletion, and anonymization across systems. This can also reduce data duplication and improve data quality. D. Setting field-level encryption across B2C Commerce, Marketing Cloud, and Service Cloud can help ensure GDPR compliance by protecting sensitive data from unauthorized access or disclosure. This can also help meet the requirements of data minimization and pseudonymization. Reference:
https://trailhead.salesforce.com/en/content/learn/modules/gdpr_basics/gdpr_basics_principles
https://help.salesforce.com/s/articleView?id=sf.mc_co_contact_key.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.b2c_commerce_security.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.field_level_encryption.htm&type=5