Which formal agreement minimizes the risk of disputes that can occur between an IT service provider and an external supplier?

An operational contract is not a standard ITIL term; the comparable internal agreement is an operational level agreement (OLA), which applies between teams within the same organization rather than with external suppliers.

An underpinning contract (UC) is a contract between an IT service provider and a third-party external supplier that underpins the provider's ability to deliver services to customers. Because it formally defines each party's responsibilities, service commitments, and remedies, it reduces ambiguity and significantly minimizes the risk of disputes arising between the provider and the supplier.

Serviceability describes the ability of a third-party supplier to meet contracted availability and reliability targets, but 'serviceability contract' is not the formal ITIL designation for the overarching agreement governing the provider-supplier relationship.

A service level contract (SLA) is an agreement between the IT service provider and the customer, not an agreement between the provider and an external third-party supplier.