Northern Trail Outfitters (NTO) wants to send an email to all Contacts who have signed up for its newsletter, but have not joined its loyalty…

When using a Salesforce Report from Sales or Service Cloud as the audience for a Marketing Cloud email send via Marketing Cloud Connect, the report must contain the Contact ID (or Lead ID). Marketing Cloud uses this unique 18-digit identifier to map the email recipient to the specific Contact or Lead record in the CRM. This ensures that tracking data, such as opens and clicks, is correctly associated with the right individual's record in Sales Cloud.

A. Individual ID: The Individual ID is related to data privacy and consent objects and is not the primary key used for identifying subscribers in a send.

C. CampaignMember ID: This ID would be the primary identifier if sending to a Salesforce Campaign, but the scenario specifies sending to a Report of Contacts.

D. External ID: While an External ID can be used for custom integrations, the standard Marketing Cloud Connect send process requires the native Salesforce Contact or Lead ID.

1. Salesforce Help, Marketing Cloud Connect, Salesforce Data Extensions, "When you send to a Salesforce report or campaign that contains contacts, the send uses the Contact ID as the SubscriberKey."

2. Salesforce Help, Marketing Cloud Connect, Create a Salesforce Report, "To use a report in a Marketing Cloud send, ensure that the report contains a Contact ID or Lead ID field."