Which document defines the agreed level of service between an IT provider and a customer?
An SLA defines the agreed service level between provider and customer.
Why this answer
A Service Level Agreement (SLA) is a documented agreement between the service provider and the customer defining the level of service. Option A is correct. Option B (OLA) is an internal agreement between teams.
Option C (UC) is a contract with a third party. Option D (CIR) is not an ITIL term.