In Which Two Ways Does the IPv6 First-Hop Security Binding

In which two ways does the IPv6 First-Hop Security Binding Table operate? (Choose two.)

A) by IPv6 HSRP to make sure neighbors are authenticated before being used as gateways
B) by various IPv6 guard features to validate the data link layer address
C) by the recovery mechanism to recover the binding table in the event of a device reboot
D) by IPv6 routing protocols to securely build neighborships without the need of authentication
E) by storing hashed keys for IPsec tunnels for the built-in IPsec features