Final answer:
Optio A , B and d are correct. A contact may fail to enter a Journey Builder interaction if they already exist and the interaction allows re-entry only after exiting, if they did not meet the entry criteria, or if the entry event needed to trigger their entry was not fired via Automation Studio.
Step-by-step explanation:
A contact might fail to enter a Journey Builder interaction for various reasons. In the context of Salesforce Marketing Cloud (SFMC), the following three reasons are relevant:
- The interaction allows re-entry only after exiting, and the contact is currently active within the journey. This is because Journey Builder typically prevents duplicate entries from being processed at the same time to ensure that each contact is only on their unique path within the interaction.
- The contact did not meet the entry criteria. Before a contact can enter a journey, they must meet specific criteria defined in the entry event. If the criteria are not met, the contact will not be allowed to enter the journey.
- The entry event was not fired via Automation Studio. Journeys may require an entry event to be triggered for contacts to enter; if the automation designed to trigger the entry event wasn't run, no contacts would be able to enter the journey.
Note that the 'High Water Mark' mentioned is a concept relating to the efficient processing of data in Journey Builder rather than a reason for an individual contact not entering a journey.