What consideration should a consultant provide to the customer?

A customer wants to create a mobile app that requires users to log in or register before accessing their data. Their source of truth is Sales Cloud which is connected to Marketing Cloud. Users who log in with existing credentials will have their device associated with their ContactKey. Users who register with the mobile app will not have their devices associated with a ContactKey for up to 24 hours.

What consideration should a consultant provide to the customer?
A . All mobile app users will create additional Contacts in Marketing Cloud.
B . User device data is unavailable in Contact Builder for up to 24 hours.
C . Existing users will create additional Contacts in Marketing Cloud.
D . Newly registered users will create additional Contacts in Marketing Cloud.

Answer: B