What action should be taken if a third party is sending a message for the customer outside of the Marketing Cloud?

Subscribers are collected on a customer’s website whose subscription database of record is Salesforce Marketing Cloud. The customer sends up to 5 emails per week based on subscriber activity.

The list is:

* Compiled in a database in the website Content Management System (CMS).

* Imported into Marketing Cloud nightly at 11 p.m.

What action should be taken if a third party is sending a message for the customer outside of the Marketing Cloud?
A . Engagement metrics will be passed into Marketing Cloud.
B . They will need to integrate with the Marketing Cloud SOAP AP
D . Unsubscribes should be synchronized between senders.
E . The third-party send list should be pulled from the CMS

Answer: B