switchport mode dynamic auto. Switching features such as trunks and EtherChannels are controlled by negotiation mode, encapsulation, VLAN membership, and whether the selected protocol is Cisco proprietary or standards based. Cisco CCNA 200-301 v1.1 includes this topic under Network Access, so the answer must be validated against normal Cisco device behavior and the operational wording of the scenario. The key is not simply recognizing a familiar acronym; it is identifying what the feature does, where it is configured, and what result it produces. The incorrect options either disable negotiation, select the wrong negotiation protocol, or configure a mode that cannot form the requested link under the stated conditions. In a real network, selecting the wrong option would either leave the feature nonfunctional, create a forwarding or security gap, or send troubleshooting in the wrong direction. The selected answer is the only one that matches the stated requirement and the way Cisco switching, routing, services, security, wireless, or automation functions are expected to operate. This is why the verified answer remains the best technical choice for the question.