The multi-level SLA' is a three-layer structure. Which one of the following layers is NOT part of this type of SLA?

Customer level is the second tier of the multi-level SLA structure, addressing requirements and issues relevant to a specific customer group or department.

Service level is the third tier of the multi-level SLA structure, covering all issues relevant to a particular service as it applies to the relevant customer group.

Corporate level is the first tier of the multi-level SLA structure, covering generic SLA issues common to all customers throughout the organization.

The multi-level SLA in ITIL Service Level Management consists of three tiers - corporate level for organization-wide issues, customer level for issues specific to a business unit or customer group, and service level for issues specific to individual services. 'Configuration level' is not a defined tier in this structure and has no basis in ITIL SLA documentation.