Who is responsible for providing ATC in a TMA?
It depends.

Air traffic control service in a TMA can be provided by either an air traffic control tower (TWR), an approach control unit (APP), or an area control unit (ACC) - or any combination of those.

A TMA is typically considered to be APP airspace, but there is no rule preventing a TWR or ACC from covering a TMA, and there are many examples of this happening throughout the world.

The typical division, if you need a simple answer, is:


TWR provides service in a control zone (CTR)
APP provides service in a TMA
ACC provides service in a control area (CTA)