The correct answer is D. By default, all VLAN traffic is tagged to traverse a trunk link except the native VLAN. In HPE Aruba Networking AOS-CX, a trunk interface can carry traffic for multiple VLANs, and VLAN tagging is used to identify traffic from different VLANs across the trunk. However, the native VLAN is the exception. HPE Aruba Networking documentation explains that the native VLAN is the VLAN to which incoming untagged traffic is assigned, and by default VLAN 1 is assigned as the native VLAN for trunk interfaces. This means normal trunk behavior is that VLAN traffic is tagged, while native VLAN traffic can be untagged unless configured otherwise. Option A is incomplete because it ignores native VLAN behavior. Option B is incorrect because the native VLAN concept applies to trunk interfaces generally, not only when a port is part of a LAG. Option C is incorrect because VLAN trunking applies to Layer 2 interfaces, not routed ports. Therefore, the default trunk behavior is tagged VLAN traffic except for the native VLAN.