What is the purpose of the guest VLAN on a Cisco Catalyst switch?

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What is the purpose of the guest VLAN on a Cisco Catalyst switch?

A. It provides configurable guest access to devices that have a supplicant but lack local credentials.
B. It provides configurable guest access to non-supplicant devices that lack local credentials.
C. It provides configurable guest access to devices that have a supplicant when the authenticator is down or unreachable.
D. It provides configurable guest access to non-supplicant devices that have local credentials.
E. It provides configurable guest access to devices that have a supplicant when the authentication server is down or unreachable.