Northern Trail Outfitters has acquired a new company and is importing customer data to Marketing Cloud. They want to ensure commercial emails are not sent to email addresses who have previously opted-out.
Which feature should they use?

Northern Trail Outfitters (NTO) is launching a new subsidiary brand, Cloud Kicks, within the next six months. Cloud Kicks anticipates sending approximately 50,000 emails per month from a child business unit. NTO will execute a large campaign announcing and associating itself with Cloud Kicks as part of the brand kickoff and is comfortable sharing digital properties with them. Cloud Kicks wants to utilize a custom sending domain, but deliverability is a primary concern.
What approach should be recommended?

Northern Trail Outfitters (NTO) is the holding company of three subsidiaries: Universal Containers, Ursa Major Solar, and Cloud Kicks. NTO recently purchased Marketing Cloud and has asked its consultant to recommend a scalable business unit (BU) hierarchy. They don't plan on executing any marketing campaigns on behalf of the NTO holding company, but NTO employees would like access to all subscribers and aggregate reporting. Additionally, each subsidiary business will be regularly running campaigns and should have their own branding, content, and subscribers.
Which solution should the consultant recommend?

Northern Trail Outfitters received a complaint today from a customer who received an email after unsubscribing last week. Today's email was sent using Marketing Cloud Connect (MCC), though last week was sent when an external system dropped a file on the Marketing Cloud SFTP and triggered a User-Initiated Send through an automation.
What could be the reason the customer received the email through MCC?

Northern Trail Outfitters is migrating from a legacy emailing tool to Marketing Cloud. As part of the migration, they have to go through a security review. Their data privacy team has made it clear that the data in the sandbox should never be mixed with data In production during testing cycles.
What recommendation would a consultant provide on the architecture to fulfill this requirement?