What can a user do to ensure that contacts enter this interaction successfully based on the error message?

A user receives a message stating that there is an error binding data bound member when testing an Entry Event in Journey Builder.

What can a user do to ensure that contacts enter this interaction successfully based on the error message? (Choose two.)
A . Import new subscribers to the All Subscribers table.
B . Fire the event in both Automation Studio and the Entry Event.
C . Make sure the contact is above the High Water Mark on the source data.
D . Select a source DE with a root relationship to the contact.

Answer: CD