Final answer:
The cancer staging system is used to classify neoplasms based on site, morphology, and behavior.
Step-by-step explanation:
The classification system used to classify neoplasms according to site, morphology, and behavior is called the cancer staging system. This system is used to determine the seriousness of a cancer based on factors such as the size of the tumor and how far the cancer has spread. Staging is important for determining prognosis and appropriate treatment.