A customer has a requirement to receive a notification whenever an activation fails for aparticular...

The feature that the consultant should use to solution for this use case is C. Activation alert. Activation alerts are notifications that are sent to users when an activation fails or succeeds for a segment. Activation alerts can be configured in the Activation Settings page, where the consultant can specify the recipients, the frequency, and the conditions for sending the alerts. Activation alerts can help the customer to monitor the status of their activations and troubleshoot any issues that may arise. References: Salesforce Data Cloud Consultant Exam Guide, Activation Alerts