The IPv6 address block FF00::/8 is reserved for multicast addressing. An IPv6 multicast address is an identifier for a group of interfaces, typically on different nodes. A packet sent to a multicast address is delivered to all interfaces that have joined the corresponding multicast group. This "one-to-many" communication model matches the question's description of sending packets to a group address. The first 8 bits of a multicast address are always 1111 1111, which is FF in hexadecimal.

A. 2000::/3 is the Global Unicast Address (GUA) range, used for public, one-to-one communication, similar to public IPv4 addresses.

B. FC00::/7 is the Unique Local Address (ULA) range, used for private, one-to-one communication within a limited set of sites.

C. FE80::/10 is the Link-Local Unicast Address (LLA) range, used for one-to-one communication on a single local network segment.

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1. IETF RFC 4291

"IP Version 6 Addressing Architecture":

Section 2.7

"Multicast Addresses": "An IPv6 multicast address is an identifier for a group of interfaces... Multicast addresses are distinguished from unicast addresses by the value of the high-order octet of the addresses. A value of FF (in hexadecimal) for the high-order octet identifies an address as a multicast address." This defines the FF00::/8 block.

Section 2.5.4

"Global Unicast Addresses": Defines the 2000::/3 block.

Section 2.5.6

"Link-Local IPv6 Unicast Addresses": Defines the FE80::/10 block.

2. Cisco Press

CCNA 200-301 Official Cert Guide

Volume 1

by Wendell Odom.

Chapter 27

"Fundamentals of IP Version 6"

Table 27-2 "IPv6 Address Prefixes for Address Types": This table explicitly lists FF00::/8 for Multicast

2000::/3 for Global Unicast

FC00::/7 for Unique Local

and FE80::/10 for Link-Local addresses

directly confirming the correct and incorrect options.

3. IETF RFC 4193

"Unique Local IPv6 Unicast Addresses":

Section 3

"Address Format": This document defines the format for Unique Local Addresses

specifying the FC00::/7 prefix. "The Local IPv6 addresses are created using a pseudo-randomly allocated global ID. They have the following format: | 7 bits |1| 40 bits | 16 bits | 64 bits | | Prefix |L| Global ID | Subnet ID | Interface ID | FC00::/7 prefix..."