Which of the following network access security methods ensures communication occurs over a secured, encrypted channel, even if the data uses the Internet?

MAC filtering- method if limiting access to wireless network based on physical address of wireless NICs

RAS (Remote Access Server)- hardware and software of remote access solution

SSL VPN: Secure Sockets Layer (SSL)- uses public key to encrypt sensitive data with is sent over SSL connection and then decrypted an receiving end using private key)
virtual Private Network (VPN)- network configuration that enables a remote user to access private network

L2TP (Layer 2 Tunneling Protocol)- VPN protocol that can run on almost any connection. Has no authentication or encryption but uses IPsec for all its security needs.