You have a Microsoft 365 subscription. Your organization is frequently collaborating with external users from different companies. You have created a dynamic group in Azure AD to automatically add new and old guest users. 
How should you configure the rule syntax?

Answer options:

A.(user.objectId -ne null) and (user.userType -eq "Member")
B.(user.objectId -e external) and (user.userType -eq "Guest")
C.(user.objectId -e external) and (user.userType -eq "Member")
D.(user.objectId -ne null) and (user.userType -eq "Guest")

Correct Answer: D 
The correct expression is (user.objectId -ne null) and (user.userType -eq "Guest") – you are adding all users that have an existing user object ID with the user type “guest”. 

Option A is incorrect. This is not a valid expression
Option B is incorrect. This is not a valid expression.
Option C is incorrect. This expression will add users with the user type Member – internal tenant users.
Reference: 
To know more about grouping guest users, please refer to the link below: 

https://docs.microsoft.com/en-us/azure/active-directory/external-identities/use-dynamic-groups