Final answer:
The valid IPv6 address is option D: 2001:0db8:0000:0003:0000:ff00:0042:8329.
Step-by-step explanation:
The valid IPv6 address is option D: 2001:0db8:0000:0003:0000:ff00:0042:8329.
An IPv6 address consists of eight groups of four hexadecimal digits separated by colons. Each group represents 16 bits, and the total length of an IPv6 address is 128 bits.
In option D, all groups have valid hexadecimal digits and the correct number of digits, making it a valid IPv6 address. The other options either contain invalid characters (option B) or use the IPv4 format (option C).