Final answer:
Leading zeros in IPv6 addresses can be removed for brevity, and successive fields of all zeros can be compressed with a double colon (::). This shortens the address and avoids including unnecessary characters, leading to a more efficient and readable IPv6 notation.
Step-by-step explanation:
When dealing with IPv6 addresses, which are composed of hexadecimal numbers, you may encounter leading zeros. In IPv6 addresses, these leading zeros are not significant and their presence is purely for formatting purposes, similar to leading zeros in decimal numbers. According to IPv6 address notation rules, you can remove these leading zeros to shorten the address presentation. Specifically, any leading zeros in a single field (a set of four hexadecimal digits, or hextet) of an IPv6 address can be omitted. For example, the address 2001:0db8:85a3:0000:0000:8a2e:0370:7334 can be written as 2001:db8:85a3:0:0:8a2e:370:7334, with each set of leading zeros removed. Furthermore, if there are multiple successive fields of all zeros, they can be compressed using a double colon (::), but this can only be done once in an address to avoid ambiguity. Using our example, the compressed form would be 2001:db8:85a3::8a2e:370:7334. Therefore, answer C is correct: They can be compressed with a double colon.