Concept:An object or substance becomes a resource only when it is useful or can serve a purpose.Explanation:Utility or usability is the main factor that makes something a resource.It must be able to fulfill a need or provide value.Discovery alone does not create a resource — the item must be useful.Purification may improve a resource, but it does not define it.Extraction is a process applied to resources, not what makes them resources.Only utility decides if an object or substance is a resource.Answer:C. Utility or usability