Comprehensive and Detailed Explanation:
The correct answer is A — Event Notification Service (ENS).
ENS allows real-time event delivery for important email metrics like Sent, Delivered, Not Sent, Bounced, Opened, and Clicked.
It uses an HTTP callback mechanism to push notifications to an external system within seconds of the event happening.
❌Why others are wrong:
B: Platform Events API is for Salesforce Core, not directly tied to Marketing Cloud events.
C: Data View Exports happen on a schedule, not real-time.
D: Data Retrieves pull data but require manual or automated fetching — not event-driven.
Exact Extract from Salesforce Official Documentation:
Salesforce Help — Event Notification Service Overview:
"Use Event Notification Service (ENS) to receive near-real-time notifications for message events like Sent, Not Sent, Delivered, etc., delivered to a designated endpoint."
(Source:https://help.salesforce.com/s/articleView?id=sf.mc-transactional-api-event-notifications.htm )
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