What could be the explanation for this experience?

LenoxSoft added Engagement History metric fields to campaign page layouts in their Salesforce org. All of the values for the Engagement History metric fields are "0".

What could be the explanation for this experience?
A . The campaign is not a connected campaign so the data is not syncing.
B. The Pardot users do not have the Pardot permission set and cannot see the data.
C. The engagement with those assets happened before the fields were added to the page layouts.
D. The data hasn’t been refreshed in 24 hours so the values haven’t been updated.

Answer: A

Explanation:

https://resources.docs.salesforce.com/latest/latest/en-us/sfdc/pdf/engagement_history_implementation_guide.pdf