a) Fixing the data quality issues in Service Cloud before migrating to Marketing Cloud can help avoid duplicate or incomplete contacts in Marketing Cloud, which can affect the contact count, billing, and personalization. Data quality issues can be fixed by using tools such as Data Loader, Duplicate Management, or ETL tools. C. Mapping Contact, Lead, and Account objects within Marketing Cloud can help enable personalization by using data from Service Cloud in email content or journeys. Mapping can be done by using Marketing Cloud Connect or Customer 360 Data Manager. Reference: https://help.salesforce.com/s/articleView?id=sf.mc_co_sync_leads_and_contacts.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.mc_co_subscriber_key_migration.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.mc_co_map_salesforce_objects.htm&type=5