Final answer:
In configuring a Guest LAN on WLC, 802.1X and Web authentication are the security settings configured in the Layer 2 Security drop-down list, ensuring authenticated and regulated network access.
Step-by-step explanation:
When configuring security on a new Guest LAN using the Wireless LAN Controller (WLC) GUI, the security settings that you are most likely to configure using the Layer 2 Security drop-down list box on the Layer 2 tab are 802.1X and Web authentication. These settings control the access layer security for devices attempting to connect to the network. 802.1X provides a framework for authenticating and controlling user access to a network, using the Extensible Authentication Protocol (EAP), while Web authentication provides a simple web-based login page for guest users to gain network access.
The correct answer to the configuration options question you're asking is a) 3 and 4, which corresponds to 802.1X and Web authentication.