THIS FSMO ROLE IS RESPONSIBLE FOR TIME SYNCHRONIZATION, AMONG OTHER THINGS.

Answer:

PDC EMULATOR

ROLE NAME	SCOPE	DESCRIPTION
Schema Master	1 per forest	Controls and handles updates/modifications to the Active Directory schema.
Domain Naming Master	1 per forest	Controls the addition and removal of domains from the forest if present in root domain.
PDC Emulator	1 per domain	PDC is short for Primary Domain Controller, which was the main domain controller used with Windows NT. The PDC emulator provides backwards compatibility for NT4 clients. It also acts as the primary server for password changes and as the master time server within the domain.
RID Master	1 per domain	Allocates pools of unique identifiers to domain controllers for use when creating objects.
Infrastructure Master	1 per domain	Synchronizes cross-domain group membership changes. The infrastructure master cannot run on a global catalog server unless all DCs are also GCs.