The early stage of ERP was carried out in the 1970s through a system called ____.
选项：

A:Customer Relationship Management (CRM)
B:Database Management System (DBMS)
C:Materials Requirement Planning (MRP)
D:Decision Support System (DSS)The early stage of ERP was carried out in the 1970s through a system called Materials Requirement Planning (MRP). The focus of the MRP software was on internal production planning, calculating time requirements components, procurement, and materials planning.