Re: 200-301 topic 1 question 115

Unique local addresses use prefix fc00::/7. The first bit following the prefix indicates, if set, that the address is locally assigned. This splits the address block in two equally sized halves, fc00::/8 and fd00::/8.

The block with L = 0, fc00::/8, is currently not defined.[1] It has been proposed that an allocation authority manage it, but this has not gained acceptance in the IETF.[8][9][10]
The block with L = 1, fd00::/8 follows the following format.
https://en.wikipedia.org/wiki/Unique_local_address#:~:text=unique%20local%20addresses.-,Definition,8%20and%20fd00%3A%3A%2F8.

SO, Unique Local Addresses (ULAs) are defined in RFC 4193, and the prefix range for ULA is indeed fd00::/8 to fdff::/8.

Re: 200-301 topic 1 question 115

B is correct because the RFC 4193 tell the bit after the prefix FC00::/7 must be 1 so unique local addresses all begin with their first two digits as FD