Who is responsible for ensuring that the Request Fulfilment process is being performed according to the agreed and documented process?

The IT Director holds an organizational leadership role but is not accountable for the governance of any individual ITIL process.

The Process Owner role in ITIL is specifically accountable for ensuring the process is fit for purpose, properly documented, and followed by all parties. They monitor process performance, manage process improvements, and are responsible for governance of the process - making them the correct answer for process compliance oversight.

The Service Owner is accountable for a specific service throughout its lifecycle, not for overseeing the execution of a process.

The Customer receives the output of the process but has no responsibility for ensuring internal process compliance.