Which method of IPv6 prefix assignment relies on the prefix contained in RA messages?

The method of IPv6 prefix assignment that relies on the prefix contained in Router Advertisement (RA) messages is Stateless Address Autoconfiguration (SLAAC). When a host receives an RA message, it can automatically configure its own IPv6 address using the prefix advertised in the RA message along with its own interface identifier, which can be generated using the EUI-64 process or a random generator, depending on the host’s operating system and privacy settings.

SLAAC allows a device to create a globally unique address without the need for a DHCP server, although it can be used in conjunction with stateless DHCPv6 to obtain other configuration information like DNS servers.