Which statement is true?

A.
An IPv6 address is 64 bits long and is represented as hexadecimal characters.

B.
An IPv6 address is 32 bits long and is represented as decimal digits.

C.
An IPv6 address is 128 bits long and is represented as decimal digits.

D.
An IPv6 address is 128 bits long and is represented as hexadecimal characters.

Explanation:
http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd80
26003d.pdf
One of the key advantages IPv6 brings is the exponentially larger address space. The following
will outline the basic address architecture of IPv6.
128-bit-long addresses
Represented in hexadecimal format:
Uses CIDR principles: prefix/prefix length
x:x:x:x:x:x:x:x, where x is a 16-bit hex field
The last 64 bits are used for the interface ID