In the process of setting up the various components of Azure AD$,$ along with the default settings, Kenia enables pass$-$through authentication. However, when she tries to log in using a test account, the attempt is not successful. What is the problem?

a$.$

The wrong SQL Server Express service account was used

b$.$

Password writeback was not enabled on the on$-$premises DCs

c$.$

The incorrect computer account group was specified

d$.$

An agent on the on$-$premises DCs was not installed