B) Extended authentication (XAuth) to request the remote peer to provide a username and password This is true because extended authentication (XAuth) is a feature that allows FortiGate to request the remote peer to provide a username and password during the IPsec IKEv1 authentication process. XAuth is an extension of the IKEv1 protocol that adds an additional authentication step after the main mode or aggressive mode exchange. XAuth can be used with either pre-shared key or certificate signature as the primary authentication method, and it can provide stronger security and granular access control for IPsec VPNs12 D) Pre-shared key and certificate signature as authentication methods This is true because pre-shared key and certificate signature are two authentication methods that are supported by FortiGate for IPsec IKEv1 VPNs. Pre-shared key is a method where both peers share a secret key that is used to authenticate each other during the IKEv1 exchange. Certificate signature is a method where both peers have digital certificates that are used to verify each other's identity and public key during the IKEv1 exchange. Both methods can be combined with XAuth for additional authentication