Final answer:
The technology that allows a user to securely access a company LAN across a public network is the VPN (Virtual Private Network), which ensures security and privacy for remote access.
Step-by-step explanation:
The technology that allows a user to securely access a company Local Area Network (LAN) across a public network is the VPN (Virtual Private Network). A VPN establishes a protected network connection when using public networks. VPN technology enables remote users to send and receive data across shared or public networks as if their devices were directly connected to the private network, thus ensuring security and privacy. Options such as HTTP, FTP, and DHCP do not provide the same level of secure access to a LAN across public networks. HTTP, or Hypertext Transfer Protocol, is used for transmitting web pages on the internet. FTP, or File Transfer Protocol, is used for the transfer of files between a client and a server on a network. DHCP, or Dynamic Host Configuration Protocol, is a network management protocol used to automate the process of configuring devices on IP networks. Therefore, the correct answer is b) VPN (Virtual Private Network).