The AZ-800 study materials explain that each MMC snap-in exposes only the FSMO role(s) it manages. In particular, Active Directory Domains and Trusts is used to view/transfer only the Domain Naming Master.
The guidance states: "Active Directory Users and Computers displays the Operations Masters for the domain (PDC Emulator, RID Master, and Infrastructure Master). Active Directory Domains and Trusts displays the Operations Master for the forest naming context (Domain Naming Master)." It further instructs: "To identify the PDC emulator, open Active Directory Users and Computers, right- click the domain, select Operations Masters, and then select the PDC tab." Because the proposed action opens Operations Master from Active Directory Domains and Trusts at the root of the console tree, it will not show the PDC emulator; it shows only the Domain Naming Master. Thus, the solution does not meet the goal of identifying the PDC emulator for the domain.