As it relates to ServiceNow reporting, which of the following statements describes what a metric can do?

A. A metric is a report gauge used on homepages to display real-time data
B. A metric is a time measurement used to report the effectiveness of workflows and SLAs

C. A metric is used to measure and evaluate the effectiveness of IT service management processes

D. A metric is a comparative measurement used to report the effectiveness of flows and SLAs.