Which tunneling protocol can be described by these characteristics: 1) Handles multiple connections at the same time, 2) Provides secure authtentication and encryption, 3) Supports only IP networks, 4) Used to be focused mostly on LAN-to-LAN communication rather than dial-up protocol, 5) Works at the network layer and provides security on top of IP.以下选项中，那个隧道协议可以被描述为以下特点1.同一时间处理多个连接 2.提供安全认证和加密3.仅支持IP网络4.主要用于局域网到局域网的通信5.工作在网络层以及提供IP安全（）

• A、Hybrid L2PP
• B、IPSec
• C、L2F
• D、L2TP