Final answer:
The Link-Local Address (LLA) is the IPv6 unicast address type that is not routable between networks. It is meant for communications only within the same network segment and starts with fe80::/10. so, option D is the correct answer.
Step-by-step explanation:
The type of IPv6 unicast address that is not routable between networks is the LLA which stands for Link-Local Address. Link-Local Addresses are designed to be used for communication within a single network segment that a host is connected to, such as a LAN (Local Area Network). This type of address is not intended to be routed across different networks or the Internet. They are automatically configured on interfaces and typically start with fe80::/10.
Other types of addresses like unique local addresses (ULA) and globally unique addresses (GUA) are routable to a certain extent, where ULAs are routable within a limited scope, and GUAs are fully routable on the global Internet. An embedded IPv4 address is part of an IPv6 address that facilitates the transition from IPv4 to IPv6 and can be routed.