Which option is not a valid method to assign the lowest-order 64-bit field of an IPv6 unicast addres

Which option is not a valid method to assign the lowest-order 64-bit field of an IPv6 unicast
address?

A.
ARP

B.
manual assignment

C.
DHCPv6

D.
auto-configured based on the 48-bit MAC address

E.
auto-generated pseudo-random number