The correct answers are A and D because both tasks are supported directly in the Exchange admin center (EAC). Microsoft Learn states that administrators can manage mail flow rules in Exchange Online from the EAC under Mail flow > Rules, which includes creating and managing transport rules for organizational email handling. Microsoft Learn also states that administrators can create shared mailboxes in the EAC under Recipients > Mailboxes, where a shared mailbox can be added and then delegated to users.

Option B is incorrect because adding a custom domain is normally done in the Microsoft 365 admin center, specifically on the Domains page. Although Exchange can later work with accepted domains and related mail flow settings, the act of adding and verifying a custom domain is not an Exchange admin center task. Option C is incorrect because license assignment is handled through Microsoft 365 or Microsoft Entra administrative tools, not the Exchange admin center.