Explanation
The reason why the customer continues to receive NTO's daily digest at their old address is because the email address in All Subscribers is prioritized. All Subscribers is the master list of subscribers in Marketing Cloud that stores their email address and subscription status. When NTO sends an email to a data extension, Marketing Cloud checks if the subscriber exists in All Subscribers and uses their email address and status from there. Therefore, deleting the customer from the data extension does not affect their subscription status or email address in All Subscribers. NTO's Marketing Cloud Admin should update or delete the customer from All Subscribers instead. The other options are incorrect because:
* Data retention settings were incorrect in the data extension. Data retention settings determine how long records are kept in a data extension before they are deleted or archived. However, this does not affect the subscription status or email address of subscribers in All Subscribers.
* Contact Builder was not configured properly. Contact Builder is a tool that allows NTO to manage their contacts and their attributes across different data sources. However, this does not affect the subscription status or email address of subscribers in All Subscribers.
* The data extension was not configured as sendable. A sendable data extension is one that has an email address field and a subscriber key field that can be used for sending emails. However, this does not affect the subscription status or email address of subscribers in All Subscribers.

Explanation
IP ramp-up takes four to six weeks to be able to fully send to all 3 million customers and IP ramp-up is important to establish a positive sender reputation. These responses articulate proper IP warming, which is the process of gradually increasing email volume from a new or unused IP address to build trust and credibility with Internet Service Providers (ISPs)

Explanation
Three Filter Activities and three Send Activities to the filtered audiences are the steps that should be included in the customer's automation. Filter Activities are used to segment a data extension based on specific criteria, such as the member's renewal date. Send Activities are used to send an email to a data extension or a filtered audience.