Use A for this item. IPv6 compression removes leading zeros in each hextet and compresses one longest contiguous run of zero hextets with double colon. The address 2001:0db8:0000:0000:0700:0003:400F:572B becomes 2001:db8::700:3:400F:572B. In Cisco CCNA 200-301 v1.1, Network Fundamentals questions frequently test the practical boundary between similar features: what the feature does, where it is configured, and what problem it is meant to solve. The double colon cannot be used twice, and nonzero hextets such as 400F cannot be shortened to 4F. A clean way to validate the answer is to map the wording of the scenario to the actual device function. If the feature supplies addressing, forwarding, authentication, trunking, route selection, or controller communication, the answer must match that function exactly rather than a nearby protocol name.