A____________is an independent firm that offers connection and transaction-forwarding services to buyers and sellers engaged in EDI．
【正确答案】 D
【答案解析】解析：为买家和卖家从事EDI提供连接和事务转发服务专用增值网络，称为VAN。 其他选项WAN为广域网，LAN为局域网，VPN为虚拟专用网。