单选题 选出应填入下面一段英语中______内的正确答案。
   An Enterprise Resource Planning (ERP) is built upon a commercial (1) that promises the seamless (2) of all the information flowing through the company (2) financial, accounting, human resources, supply chain and customer information. In implementation, all ERP systems include several features. The system is installed on a typical database management system. It requires initial setup according to the organization's process, but it may be (3) according to the organization's unique process requirements through a tool set contained within the ERP applications. Using ERP, (4) can be prescribed to automate approval processes through established chains of command. One of the methods used to effect rapid implementation ofthe ERP system is to conduct concurrent (5) sessions.