Which remote access VPN technology requires the use of the IPsec-proposal configuration option?

Clientless SSL VPN operates over TLS at the application layer and does not establish an IPsec tunnel, so ipsec-proposal configuration is not applicable.

SSL VPN Full Tunnel uses TLS to encapsulate all traffic without IPsec, and its configuration uses SSL policies rather than ipsec-proposal objects.

Cisco ASA IKEv2 configuration uses a dedicated 'crypto ikev2 ipsec-proposal' object to specify encryption and integrity algorithms for IPsec security associations. This object is then referenced in IKEv2 group policies or connection profiles, and is a required element of the IKEv2 VPN configuration hierarchy that does not exist in IKEv1 syntax.

IKEv1 VPN uses 'crypto ipsec transform-set' to define IPsec parameters, not the ipsec-proposal syntax, which was introduced as part of the IKEv2 configuration model.