A) SMS opt-in will sync with Service Cloud when contact ID is the subscriber key in Marketing Cloud. This can help enable consent and profile management across the clouds by allowing customers to opt-in or opt-out of SMS messages and reflecting their preferences in both Service Cloud and Marketing Cloud. This can also help comply with industry regulations and best practices for SMS marketing. C. Profile changes in B2C Commerce will sync to Service Cloud when person accounts are used. This can help enable consent and profile management across the clouds by allowing customers to update their profile information in B2C Commerce and syncing their changes to Service Cloud. This can also help maintain consistent and accurate customer data across different systems and platforms. Reference:
https://help.salesforce.com/s/articleView?id=sf.mc_co_person_accounts.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.mc_co_implement_marketing_cloud_connect.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.b2c_commerce_integration.htm&type=5