A problem is a cause, or potential cause, of one or more incidents. Therefore, C is correct. Incident Management and Problem Management have different purposes. An incident is an unplanned interruption to a service or reduction in service quality that requires restoration. Problem Management addresses underlying causes and potential causes of incidents so that their likelihood or impact can be reduced. A known error is a problem that has been analysed sufficiently for relevant information---such as a cause or workaround---to be documented and managed. It is therefore not synonymous with every problem. An asset is any resource or capability that contributes value to products or services and is unrelated to this definition. SDA v9 includes Problem Management as one of the core ITSM practices an analyst must understand. The distinction is important because analysts should not confuse restoration of an individual incident with investigation of its underlying cause. Problem Management reduces the likelihood and impact of incidents by identifying actual and potential causes and managing workarounds and known errors.