Which statement correctly compares IPv4 and IPv6 headers in terms of address length and header structure?

• A. IPv4 headers typically 20 bytes minimum with 32-bit addresses; IPv6 headers are fixed at 40 bytes with 128-bit addresses; IPv6 uses extension headers to carry options.
• B. IPv4 uses 128-bit addresses and a 40-byte header.
• C. IPv6 headers are variable length and do not have extension headers.
• D. IPv4 headers are 60 bytes minimum and use 64-bit addresses.

Answer: (A)