Which of the following is the BEST description of a Business Case?

The ITIL glossary defines a Business Case as a decision support and planning tool that projects the likely consequences of a business action, providing justification for expenditure by documenting costs, benefits, options, issues, and risks. It is used during Service Strategy and Continual Service Improvement to initiate and authorize projects or service changes.

This describes a physical storage item and has no relevance to any ITIL concept or IT service management practice.

A complaint about a missed service level relates to Service Level Management and may trigger a Service Improvement Plan, not a Business Case.

Terms and conditions in an outsource contract are legal and commercial documents that fall under supplier management, not the definition of a Business Case.