Use B for this item. The spanning-tree root bridge is selected by the lowest bridge ID for the VLAN. The bridge ID combines bridge priority and MAC address, so the switch with the numerically lowest effective value becomes root for VLAN 110. In Cisco CCNA 200-301 v1.1, Network Access 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. Physical placement and port count do not decide the STP root; only the STP election values do. 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.